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Title: An Anatomical Disquisition on the Motion of the Heart & Blood in Animals: The Circulation of the Blood
Author: Harvey, William Fryer
Language: English
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  An Anatomical
  Disquisition on
  of the HEART
  & BLOOD in
  Translated from
  the Latin by

  London: J·M·Dent & Co.
  New York: E·P. Dutton & Co.



However much the renewal of classical learning in the fourteenth,
fifteenth, and sixteenth centuries may have furthered the development
of letters and of art, it had anything but a favourable influence on
the progress of science. The interest awakened in the literature of
Greece and Rome was shown in admiration not only for the works of
poets, historians, and orators, but also for those of physicians,
anatomists, and astronomers. In consequence scientific investigation
was almost wholly restricted to the study of the writings of authors
like Aristotle, Hippocrates, Ptolemy, and Galen, and it became the
highest ambition to explain and comment upon their teachings, almost
an impiety to question them. Independent inquiry, the direct appeal
to nature, were thus discouraged, and indeed looked upon with the
utmost distrust if their results ran counter to what was found in
the works of Aristotle or Galen. This spell of ancient authority was
broken by the anatomists of the sixteenth century, who determined at
all costs to examine the human body for themselves, and to be guided
by what their own observations revealed to them; and it was finally
overcome by the independent genius of two men working in very different
scientific spheres, Galileo and Harvey. These illustrious observers
were contemporaries during the greater part of their lives, and were
some years together at the famous University of Padua. Galileo and
Harvey refused to be bound by the teachings of Aristotle and Galen, and
appealed from these authorities to the actual facts of nature which any
man could observe for himself. Their scientific work is therefore of
interest, not only for the innate value of the discoveries they made,
but also because it shows them as pioneers in that independent spirit
of scientific inquiry to which the great advance in natural knowledge
since their time is so largely due.

Harvey’s work, by which his name has been made immortal, strikingly
illustrates this. He was the first to show the nature of the movements
of the heart, and how the blood moved in the body. He did so by putting
on one side authority, and directly appealing to observation and
experiment. The completeness of the success with which this independent
line was taken, as exemplified in his treatise “On the Movement of the
Heart and Blood,” is such as to excite the admiration of every modern
physiologist. “C’est un chef-d’œuvre,” says a distinguished French
physiologist, Flourens, “ce petit livre de cent pages est le plus beau
livre de la physiologie.”[1]

  [1] Flourens, Histoire de la Découvert de la Circulation du Sang,

The discovery made by Harvey was this: That the blood passed from the
heart into the arteries, thence to the veins, by which it was brought
back to the heart again; that the blood moved more or less in a circle,
coming back eventually to the point from which it started. In a phrase,
there was a Circulation of the Blood. Moreover, this circulation
was of a double nature--one circle being from the right side of the
heart to the left through the lungs, hence called the Pulmonary or
Lesser Circulation; the other from the left side of the heart to the
right, through the rest of the body, known as the Systemic or Greater
Circulation. Further, that it was the peculiar office of the heart to
maintain this circulation by its continuous rhythmic beating as long as
life lasts.

This appears very plain and simple to us now--so easy that he who runs
may read: as important as simple, for without this knowledge it is no
exaggeration to say that a real understanding of any important function
of the human body was impossible. And hence it has been contended with
much force that not only the science of physiology, but the scientific
practice of medicine date from this discovery. “To medical practice,”
says Sir John Simon, “it stands much in the same relation as the
discovery of the mariner’s compass to navigation; without it, the
medical practitioner would be all adrift, and his efforts to benefit
mankind would be made in ignorance and at random.... The discovery is
incomparably the most important ever made in physiological science,
bearing and destined to bear fruit for the benefit of all succeeding

  [2] Harvey Tercentenary Memorial Meeting, Folkestone, September 6,

When Harvey first approached the subject, there were all kinds of
crude and fantastic ideas regarding the functions and uses of the
heart, bloodvessels, and blood--that the heart was the workshop in
which were elaborated the spirits, a due supply of which was necessary
for many parts of the body; that from the heart the arteries carried
spirits, the veins nutriment to the different parts of the body; that
the arteries contained blood and air mixed together, or only air; that
fuliginous vapours, whatever they may be, passed from the heart along
the bloodvessels; that the septum of the heart, by which its two sides
are completely separated, was riddled with minute holes, like a fine
sieve, through which the blood percolated from the right to the left
side; again, that the heart was the organ in which the heat of the body
was produced. Another favourite theory was that the blood moved from
the heart along certain bloodvessels and back again by exactly the same
channels, after the manner of the rise and fall of the tides, to which
in fact the movement was likened. More curious still, even the best
informed appeared to believe that the arteries terminated in nerves.

Notwithstanding these curious and erroneous speculations there was
not wanting exact and wide knowledge of the anatomy of the human
body. Indeed, before Harvey was born there had lived and died a most
remarkable man known to fame as the “Father of Anatomy.” This was
Vesalius. Vesalius’s knowledge of the human body was so profound that
the only wonder is that he did not forestall Harvey in the discovery
of the circulation. As the result of dissections of the body at the
time when they could be carried out only with great difficulty, and
often at the risk of severe penalties, Vesalius published, when only
twenty-eight years of age, a treatise on Anatomy[3] which cannot fail
to excite the astonishment and admiration of any modern acquainted with
the subject. This work is illustrated with fine engravings made from
drawings by John Calcar, a Flemish artist, and pupil of Titian.[4]

  [3] De humani Corporis fabrica, 1543.

  [4] Vasari: “Lives of the Painters,” vols. iii. 519, v. 402
  (Bohn’s ed.).

The distribution of the bloodvessels in the lungs and many other parts
of the body, the general structure of the heart, the valves in the
veins, were all known before Harvey arrived on the scene. More than
this, the circulation through the lungs, or the Pulmonary Circulation,
appears to have been known to one person at least. Michael Servetus,
famous for his martyrdom on account of his religious opinions, in one
of his theological works[5] does actually describe the blood as passing
from the right side of the heart to the left through the lungs, and
gives good reasons for his belief. Servetus, in his early days, had
been with Vesalius prosector to John Guinterius of Andernach when
Professor of Anatomy at Paris. Guinterius[6] speaks with admiration of
the knowledge and abilities of his two young assistants. Like Vesalius,
Servetus was therefore well acquainted with the anatomy of the body;
but more, he was a physiologist; and no doubt when the cruelty of
theological dispute sent him to the stake at the age of forty-four, it
deprived physiology of a most promising investigator. The book in which
the account of the Pulmonary Circulation is found has a most curious
history. All copies of it, except one, were burnt with Servetus. This
copy became the property of D. Colladon, one of his judges. After
passing through the library of the Landgrave of Hesse-Cassel it came
into the hands of a Dr. Mead, who undertook in 1723 to issue a quarto
edition of it, but before completion the sheets were seized at the
instance of Dr. Gibson, Bishop of London, and destroyed. The Duc de
Valise is said to have given 400 guineas for the original copy, and at
his sale it brought 3,810 livres. It is now in the National Library at
Paris. It may well be questioned therefore whether the discovery of
Servetus was ever known to the anatomists, including Harvey, who wrote
after his death. One of these was Realdus Columbus, who published a
work on Anatomy[7] six years after Servetus died, in which he shows
that he clearly understood the valves of the heart, and describes the
passage of the blood through the lungs. Columbus has been claimed
as the real discoverer of the circulation and as having forestalled
Harvey. But neither Servetus nor Columbus had any notion of the Greater
or Systemic Circulation. And the latter actually says the heart is not
muscular, and speaks of a to-and-fro movement of the blood in the veins.

  [5] Restitutio Christianismi, 1553.

  [6] Institutiones Anatomici, Epistola Nuncupatoria, 1539.

  [7] De Re Anatomica, 1559.

But a third and much more serious precursor of Harvey as the discoverer
has been brought forward in the person of Andreas Cæsalpinus[8] of
Arezzo, justly renowned as the earliest of botanists. He actually used
the word “circulation” in regard to the passage of the blood through
the lungs. The claims of Cæsalpinus have been taken up with enthusiasm,
not to say bitterness, in Italy; and in 1876 his statue was erected
with much pomp and speechmaking in Rome, and an inscription placed
upon it recording that he was the first discoverer of the circulation
of the blood. It is much to be regretted that this display was not
altogether free from a desire to depreciate Harvey. Wonder may well
be expressed at this procedure, even after allowing for well-meant
patriotic ardour, when it is learnt that in his works Cæsalpinus
speaks of the arteries ending in nerves, of the septum of the heart
being permeable, and its valves acting imperfectly, and of the veins
carrying blood to the body for its nourishment. The statements made
by Cæsalpinus, which at first sight point to his knowledge of the
circulation, are altogether discounted on perusal of his works, and
it becomes impossible to believe that he had any clear idea of the
circulation as we understand it to-day. The misconception has no doubt
arisen from the interpretation of isolated passages in the light of
what we now know regarding the circulation. Moreover, it is impossible
to believe, seeing how well the works of Cæsalpinus were known, that,
had he ever been regarded as putting forward in them the doctrine of
the circulation as we now understand it, such a new and startling view
would not have attracted the attention of the distinguished anatomists
who were his contemporaries or immediate successors. But that none of
them ever for a moment saw any such doctrine in the works of Cæsalpinus
is shown by their writings, and by the surprise with which Harvey’s
discovery was received.

  [8] Quæstiones Peripateticæ, 1569. De Plantis, 1583.

Even Shakespeare has been cited as being acquainted with the
circulation of the blood, because he refers to its movement. This only
illustrates the confusion which has often been made of movement with
circulation. From the earliest times it had been believed there was
movement of the blood, but there was no clear or correct idea as to
the nature of the movement. The view may be ventured that another
confusion is responsible for a good deal that has been said about
Harvey having been forestalled in the discovery. It is confusing the
passage through the lungs of _some_ blood with the _whole mass_ of
it. It is difficult to believe, on taking a broad view of all their
statements on the subject, that any of Harvey’s predecessors realised
that the whole mass of the blood was continually passing through the
lungs. Had they done so it is further difficult to see how the systemic
circulation should have escaped them. But of this they certainly had no

We may admit all this previous knowledge without its detracting from
the greatness and merit of Harvey’s work. Although the same anatomical
facts, and even a glimmering of the Pulmonary Circulation may have been
present to the minds of his predecessors or contemporaries, yet the
genius, the spark of originality by which was discovered the proper
relation to one another of the former, the true significance and
meaning of the latter, belongs to Harvey and to him alone.

As was said by one of the best informed minds[9] of the eighteenth
century: “It is not to Cæsalpinus, because of some words of doubtful
meaning, but to Harvey, the able writer, the laborious contriver
of so many experiments, the staid propounder of all the arguments
available in his day, that the immortal glory of having discovered the
Circulation of the Blood is to be assigned.”

  [9] Haller, Elementa Physiologiæ, vol. i. lib. iii., 1757.

William Harvey was born on April 1, in the year 1578, at Folkestone,
the eldest of seven sons of a well-to-do Kentish yeoman. When ten years
old he was sent to the Grammar School at Canterbury, and remained there
until he was fifteen. He then proceeded to Caius College, Cambridge,
where after three years’ residence he took the usual degree. Desiring
to enter the medical profession, he adopted a course, not unusual
at that time, of going abroad to study at a Continental University,
a course due to the absence of scientific teaching in the English
Universities on the one hand, and to its excellence in those of the
Continent on the other. Consequently, in the year 1597, when nineteen
years of age, Harvey directed his steps towards Padua, then famous
throughout Europe for its medical school, and especially for its school
of anatomy. Earlier in the century the chair of Anatomy had been filled
by Vesalius; it was now occupied by another celebrated anatomist,
known as Fabricius of Aquapendente. Harvey enjoyed the advantage of
studying anatomy under this great teacher, and the visitor to Padua
to-day can see the little anatomical theatre with its carved desks,
over one of which, no doubt, our illustrious discoverer leant with
eager attention whilst Fabricius demonstrated on the body below. We
can see the professor with pride explaining to his pupils the valves
in the veins which he had discovered, yet not appreciating their
meaning and importance; that was to be done a few years hence by the
young student listening above. It is very interesting to learn that
at this time Galileo was also a professor at Padua, and was lecturing
with such success that students flocked to hear him from all parts
of Europe. Surely it is difficult to imagine any seat of learning
more distinguished and attractive than the University of Padua must
have been during the five years Harvey spent there. At the end of
this time he received his degree of doctor, the diploma for which is
couched in the most eulogistic language, showing how by his studies and
abilities he had attracted the attention and earned the commendation
of the distinguished professors who then held the chairs of Anatomy,
Medicine, and Surgery in the University. He now returned to England,
and was granted the degree of Doctor of Medicine by the University of

Soon after, Harvey settled in London and began to practise. In 1607
he was elected a Fellow of the Royal College of Physicians, and in
1615 was appointed Lecturer in Anatomy to that ancient and important
foundation. In 1609 he had been elected physician to St. Bartholomew’s

In 1616, the year Shakespeare died, Harvey probably began in his
classes to teach that doctrine which has immortalised his name. He
began to show his pupils, and whoever else desired to be present,
from dissections of the human body and of animals, and by experiment
when necessary, the true office of the heart, the true course of the
movement of the blood in the body. This he continued to do for more
than ten years, listening patiently to objections, indeed inviting
criticisms so that the complete truth might be discovered free from
any falsities or misconceptions. At last, upon the earnest entreaties
of his most distinguished medical friends, he was persuaded to publish
his discovery to the world. These facts are of interest in throwing
some light on Harvey’s character. A discoverer who waits years before
publishing what he is firmly convinced in his own mind is a new idea,
not to say a great discovery, must be possessed of that calmness
of mind and abnegation of self which we associate with the true
philosopher. A discoverer who employs so long an interval to give
opportunity for criticism, and to deal with objections, must indeed be
wedded to truth.

This devotion to truth, however, had its reward, for it resulted in
one of the most remarkable scientific treatises ever written. When, in
1628, Harvey published at Frankfort-on-Main, his book on “The Movement
of the Heart and Blood,” he gave his reasons for believing the blood to
circulate, and explained the use of the heart in language so simple,
so clear, so exact, that now, nearly three hundred years afterwards,
the most accomplished physiologist can hardly improve on it. This
assuredly is a fact almost unique in the history of science.

And yet with all this the fact remains that Harvey never really knew,
from the nature of the case could not know, how the blood passed from
the arteries to the veins--how, in other words, an essential part
of the circulation was actually accomplished. The blood passes from
the arteries to the veins through minute microscopic tubes termed
capillaries. In Harvey’s day the microscope was not sufficiently
powerful to reveal such fine structures to human vision, and he was
therefore necessarily ignorant of their existence. Looked at from this
point of view, the discovery affords a very good example of what has
been aptly termed the scientific use of the imagination. Although, with
his imperfect microscope, it was impossible for him to know how the
blood actually passed from the arteries to the veins, yet as the result
of his observations and experiments he was able to infer and to state
the grounds for his inference in clear, forcible, and most convincing
language, that the blood must circulate, and circulate in one direction
only, viz. from the heart into the arteries, thence to the veins, by
which it was brought back to the heart again. His imagination was thus
enabled to bridge over the gulf between the arteries and veins which
his eyes, with the imperfect instrument then alone at his disposal,
were quite unable to cross. It was not until four years after Harvey’s
death that the microscope had been sufficiently improved to enable an
Italian anatomist named Malpighi,[10] in the year 1661, to actually
observe the capillaries uniting by their networks arteries and veins.

  [10] De Pulmonibus, Observationes Anatomici, 1663.

The work was published at Frankfort doubtless that it might be more
easily disseminated over the Continent. It made a sensation among
the learned of all countries. Its conclusions were opposed by the
older physicians; but by the younger scientific men it was by no
means received with disfavour. Amongst the latter was the philosopher
Descartes, whose name was then a power in Europe. The philosophical,
yet keenly practical mind of Descartes grasped the discovery with
avidity and supported it with ardour. In his celebrated “Discours de la
Méthode,”[11] he refers to the discovery of “an English physician,” and
describes with enthusiasm the anatomy and use of the heart. Although
we have no certain information on the point it is quite possible that
Descartes may have known Harvey, for in the year 1631 he is said to
have paid a visit to England; and in his second reply to Riolan Harvey
refers to “the ingenious and acute Descartes,” and says the honourable
mention of his name demands his acknowledgments. Thus the discovery
became widely known and largely adopted.

  [11] First published at Leyden in 4to, 1637.

One result of the publication of his discovery was only in keeping with
the experience of many great and original minds before and after his
time. In the things of this world his discovery was of little service
to him. His practice fell off. Patients feared to put themselves
under the care of one who was accused by his envious detractors of
being crack-brained, and of putting forward new-fangled and dangerous
doctrines. One who knew Harvey writes as follows: “I have heard him
say that after his booke of the Circulation of the Blood came out he
fell mightily in his practice, and ’twas believed by the vulgar that
he was crack-brained, and all the physitians were against him, with
much adoe at last in about 20 or 30 years time it was received in all
the universities in the world, and as Mr. Hobbs says in his book ‘De
Corpore,’ he is the only man perhaps that ever lived to see his own
doctrine established in his lifetime.”[12]

  [12] John Aubrey, “Lives and Letters of Eminent Persons,” London,

There was one striking exception to this treatment. The King, Charles
I., not only appointed Harvey his physician, but showed the liveliest
interest in his discovery. Harvey explained his new doctrine on the
body before the King. Whatever opinions may be held regarding the
moral and political character of that unfortunate monarch, it must be
admitted that in aiding and befriending Vandyke and Harvey he showed
himself an enlightened patron of both art and science. Harvey continued
the King’s physician, and held this position when, in 1641, Charles
declared war against the Parliament. It is here curious to learn that
although openly declared enemies the Parliament was still mindful
of the King’s person, for not only with their consent, but by their
desire, Harvey remained his physician.[13] Notwithstanding his intimate
connection with the Court, Harvey appears to have taken no active part
in the great political struggle now taking place. The little solicitude
he had for it is shown by an anecdote told of him at the first battle
of the Civil War. “When King Charles,” says a contemporary author,[14]
“by reason of the tumults left London, Harvey attended him, and was
at the fight of Edgehill with him: and during the fight the Prince
and the Duke of York were committed to his care. He told me that he
withdrew with them under a hedge, and tooke out of his pocket a booke
and read. But he had not read very long before a bullet of a great gun
grazed on the ground near him, which made him remove his station.”
This anecdote well illustrates Harvey’s calm and peaceful character.
This was also shown by the restrained and dignified manner in which he
treated the many writers who attacked him, sometimes in anything but
choice language, after the publication of his great discovery. Anything
like controversy for controversy’s sake was wholly foreign to his
nature. “To return evil speaking with evil speaking,” he remarks in a
reply to one of his critics, “I hold to be unworthy of a philosopher
and a searcher after truth. I believe I shall do better and more
advisedly if I meet so many indications of ill breeding with the light
of faithful and conclusive observation.”[15] To many of the attacks
made on his discovery or on himself, he therefore did not condescend
to reply. And when from the eminence of his opponents he felt called
upon to do so, he replied with the utmost courtesy and kindliness. But
whilst admitting the high claims to distinction on other grounds of
his antagonist, he proceeded on this particular question to utterly
demolish him with clear facts and stern irrefutable arguments and
experiments. He called upon his opponents to observe the facts and
make the experiments for themselves, instead of citing the opinions
of authors centuries old, or making long discourses on spirits,
fuliginous vapours, and the tides of Euripus. This is well illustrated
in his replies to Riolan. The arguments of Riolan would hardly seem
to have entitled him to the honour of the special notice of the great
discoverer. But probably his position as Anatomist in the University
of Paris, and of physician to the Queen-Mother, Marie de Medicis, made
Harvey pick out his criticisms as a suitable excuse for replying to his
opponents. Harvey’s mode of argument is well shown by the following
admirable remarks on the Manner and Order of Acquiring Knowledge, in
his introduction to the work on “The Generation of Animals”: “Sensible
things are of themselves and antecedent; things of intellect however
are consequential and arise from the former, and indeed we can in
no way attain to them without the help of the others. And hence it
is that without the due admonition of the senses, without frequent
observation and reiterated experiment, our mind goes astray after
phantoms and appearances. Diligent observation is therefore requisite
in every science, and the senses are to be frequently appealed to.
We are, I say, to strive after personal experience, not to rely on
the experience of others: without which indeed no one can properly
become a student of any branch of natural science.” Referring to his
own particular work he says: “I would not have you therefore, gentle
reader, to take anything on trust from me concerning the Generation
of Animals: I appeal to your own eyes as my witness and judge. For as
all true science rests upon those principles which have their origin
in the operation of the senses, particular care is to be taken that
by repeated dissection the grounds of our present subject be fully
established.... The method of investigating truth commonly pursued at
this time therefore is to be held erroneous and almost foolish, in
which so many inquire what others have said, and omit to ask whether
the things themselves be actually so or not.”

  [13] De Generatione Ex. lxviii.

  [14] Aubrey, _loc. cit._

  [15] _Vide_ Second Reply to Riolan, p. 133 post.

When the King made Oxford his headquarters, Harvey was with him,
and was appointed head of Merton College. But in 1646, on Oxford
surrendering to the Parliamentary forces, he gave up his wardenship
and quitted the city. Having no call to take an active part in the
political contest, and now verging on threescore-and-ten, he retired
from his position of physician to the King and went to London, where
he was hospitably entertained in the houses of his brothers, who were
wealthy merchants in the City. Here he no doubt once again devoted
himself to scientific observation, the nature of which became evident,
when in 1651 he was persuaded, somewhat against his own inclination,
by his friend, Dr. George Ent, to allow the publication of his book
on “The Generation of Animals.” In this work he appears as a pioneer
in the difficult science of Embryology, working under most adverse
conditions, for he had no microscope worthy of the name. Whilst,
therefore, of no great value in the light of our present knowledge, it
is a monument of the author’s industry and of his enthusiastic devotion
to physiological research. It contains a great number of acute and
interesting observations; and he had evidently made many more, for
he says that his papers on the Generation of Insects were lost as a
result of the tumults which arose at the outbreak of the Civil War.
He told Aubrey that no grief was so crucifying to him as the loss
of these papers. The King took a direct personal interest in these
investigations,[16] and supplied him with deer from the Royal Parks in
order to further them.

  [16] De Generatione Ex. lxix

In two respects the work on Generation is worthy of more than a
mere passing notice, and entitles its author to the possession of
almost prophetic genius. The first is the enunciation of the great
generalisation _omne vivum ex ovo_. Although this particular phrase is
nowhere to be found, as is often erroneously stated, in the treatise on
Generation, yet a perusal of Exercises I., LI., and LXII. will convince
any one that Harvey had grasped this great idea, which has since been
so abundantly verified. The other is his doctrine of _Epigenesis_, or
the formation of the new organism from the homogeneous substance of the
germ by the successive differentiation of parts, that all parts are not
formed at once and together, but in succession one after the other. He
put forward this doctrine of Epigenesis in contradistinction to that of
_Metamorphosis_, according to which the germ was suddenly transformed
into a miniature of the whole organism which subsequently grew. This
is certainly very remarkable, and entitles him to be regarded as a
forerunner of Caspar Wolff, Von Baer, and the modern Evolutionary
School, which sees in the development of the organism from the ovum a
passage from the homogeneous to the heterogeneous by a gradual process
of differentiation, from a germ in which there is no sign of any of the
parts of the adult to an organism with all its many and varied organs.
Commenting on certain passages of Exercise XLV., in which Harvey
specially refers to this subject, the late Professor Huxley remarked:
“In these words, by the divination of genius, Harvey in the seventeenth
century summarised the outcome of the work of all those who, with
appliances he could not dream of, are continuing his labours in the
nineteenth century.”[17]

  [17] Evolution: “Encyclopædia Britannica,” 9th ed. 1878.

In addition to his long sojourn in Italy as a student, Harvey made
several other visits to the Continent. In 1630 he consented to
accompany the young Duke of Lennox in his travels abroad. He had
returned by 1632, for in that year he was formally appointed physician
to Charles I. Again, in 1636 he accompanied the Earl of Arundel on his
embassy to the Emperor, and was absent some nine months. According to
Aubrey, in 1649 Harvey, with his friend Dr. George Ent, again visited
Italy. Some doubt has been thrown on this journey, but it receives
support from a letter of Harvey’s to John Nardi, of Florence, written
on November 30, 1653, in which he concludes by asking his correspondent
to mention his name to his Serene Highness the Duke of Tuscany, “with
thankfulness for the distinguished honour he did me when I was formerly
in Florence.”

In his old age Harvey was honoured in a striking manner by those
best fitted to judge of the merit and value of his life’s work. His
statue was erected in the hall of the College of Physicians. As an
acknowledgment, as it were, of this remarkable compliment, he built at
his own expense a Convocation Hall and a Library as additions to the
College, and contributed books, curiosities, and surgical instruments
for the Library and Museum. Not content with this, he made over to the
College, the year before he died, his paternal estate, stipulating
that a certain sum out of it should be employed every year for the
delivery of an Oration in commemoration of benefactors of the College,
and of those who had added anything to medical knowledge during the
year. This Oration is annually delivered by some distinguished member
of the medical profession, and is inseparably associated with the name
of Harvey. This graceful act shows how in his declining years Harvey’s
thoughts were turned to the future. It had for its object to further
the progress of scientific knowledge, to stimulate studies in the
pursuit of which he had shown himself such a master. He wished when old
and infirm, bereft of the power of again entering the arena of active
work and investigation, to still do something to increase and extend
that knowledge which is of so great service to mankind--a knowledge of
the human body in health and in disease.

Harvey died on June 3, in the year 1657, in the eightieth year of his
age, and was buried at the village of Hempstead, in Essex, in a vault
which had been built by his brother Eliab.


  LONDON, _November, 1906_.

The following is a list of Harvey’s works, and of the more important
references to his life and discovery:--

  “MS. Memorandum Book,” dated 1616, entitled “Prælectiones Anatomicæ
  Universalis.” It is in Harvey’s handwriting, and contains the
  origin of the Circulation. (In the British Museum.) A Facsimile was
  published in 1886 by the College of Physicians.

  “MS. De Musculis,” 1627, in Harvey’s handwriting. (Brit.
  Mus.) A Notice on this manuscript was published in 1850 by
  G. E. Paget, M.D.

  “MS. of Prescriptions,” 1647. (Brit. Mus.)

  “MS. Diploma of Doctor of Medicine” to Harvey by University of Padua,
  April 25, 1602. (In the College of Physicians.)

  “MS. Illuminated Grant of M.D.,” by University of Padua to an
  Englishman, Thomas Heron, which is witnessed by “Guigliomo Harveo
  Consiliaris Magnificæ Nationis Anglæ.” It is dated March 19, 1602.
  (Brit. Mus.)

  “MS. Oratio Harveiana,” 1661, ab. E. Greaves. (Brit. Mus.)

  “De Motu Cordis et Sanguinis,” Frankfort-on-Main, 1628. First English
  edition published by R. Lowndes, with preface by Zachariah Wood,
  Physician of Rotterdam, 1653.

  “Anatomical Examination of the Body of Thomas Parr, aged 152 years,”
  made in 1635, but not published until 1669 in Betts’ “De Ortu et
  Natura Sanguinis.”

  “Two Disquisitions in Reply to John Riolan, jun.,” 1649.

  “De Generatione Animalium,” London, 1651; in English, 1653.

       *       *       *       *       *

  “Biographica Britannica,” 1750. The Life of Harvey, containing much
  curious information and discussion, is evidently that on which all
  subsequent biographies are based.

  “Harveii Opera Omnia,” edited by Dr. Akenside, with Life by Thomas
  Lawrence, M.D., 1766.

  “Lives and Letters of Eminent Persons,” by John Aubrey, 1813.

  “Records of William Harvey, with Notes,” by James Paget, of St.
  Bartholomew’s Hospital, 1846.

  “The Works of William Harvey,” translated by Robert Willis, M.D.
  (Sydenham Society, 1848). This excellent translation has been
  followed in the present volume.

  “Histoire de la Découverte de la Circulation du Sang,” par
  M. J. P. Flourens, 1854.

  “Circulation of the Blood: its History, Cause, and Course,” by
  G. H. Lewes in “Physiology of Common Life,” 1859.

  “Memorials of Harvey,” collected by J. H. Aveling, 1875.

  “William Harvey: a history, etc.,” by Robert Willis, M.D., 1878.

  “Roll of the Royal College of Physicians,” by William Munk, M.D., 2nd
  ed., 1878.

  Huxley on “Evolution,” in “Encyclopædia Britannica,” 9th ed., 1878.

  “Experimental Physiology,” by Sir R. Owen, 1882.

  “A Defence of Harvey,” by George Johnson, M.D., 1884.

  “Masters of Medicine: William Harvey,” by D’Arcy Power 1897.


In the present edition of Harvey’s Treatise on the Circulation of the
Blood, which is reprinted from the Sydenham Society’s edition of 1847,
the footnotes by Willis, the editor and translator of that edition, are
distinguished by brackets from Harvey’s original notes.




  EDITOR’S INTRODUCTION                                             vii

  DEDICATION                                                          3

  INTRODUCTION                                                        9


  I. THE AUTHOR’S MOTIVES FOR WRITING                                22

        LIVING ANIMALS                                               24

        LIVING ANIMALS                                               28

        BODIES OF LIVING ANIMALS                                     31


        VENTRICLE OF THE HEART                                       42

        AND LEFT VENTRICLE                                           49

        OF THE BLOOD                                                 55

        THE FIRST PROPOSITION                                        58

        BY EXPERIMENT                                                64

  XI. THE SECOND POSITION IS DEMONSTRATED                            67

        SECOND POSITION DEMONSTRATED                                 75

        THE BLOOD IS DEMONSTRATED FROM IT                            78


        PROBABLE REASONS                                             86

        CERTAIN CONSEQUENCES                                         90


        BLOOD, ADDRESSED TO JOHN RIOLAN                             111



  TO CASPAR HOFMANN, M.D.                                           175

  TO PAUL MARQUARD SLEGEL, OF HAMBURG                               176


  IN REPLY TO R. MORISON, M.D., OF PARIS                            185



        PHYSICIAN AT THE COURT OF HESSE-DARMSTADT                   197

        ALIKE FOR HIS VIRTUES, LIFE, AND ERUDITION                  199

        AT HARLEM                                                   200


        MADE BY WILLIAM HARVEY                                      205


  INDEX                                                             223










The heart of animals is the foundation of their life, the sovereign
of everything within them, the sun of their microcosm, that upon
which all growth depends, from which all power proceeds. The King, in
like manner, is the foundation of his kingdom, the sun of the world
around him, the heart of the republic, the fountain whence all power,
all grace doth flow. What I have here written of the motions of the
heart I am the more emboldened to present to your Majesty, according
to the custom of the present age, because almost all things human are
done after human examples, and many things in a King are after the
pattern of the heart. The knowledge of his heart, therefore, will not
be useless to a Prince, as embracing a kind of Divine example of his
functions,--and it has still been usual with men to compare small
things with great. Here, at all events, best of Princes, placed as you
are on the pinnacle of human affairs, you may at once contemplate the
prime mover in the body of man, and the emblem of your own sovereign
power. Accept therefore, with your wonted clemency, I most humbly
beseech you, illustrious Prince, this, my new Treatise on the Heart;
you, who are yourself the new light of this age, and indeed its very
heart; a Prince abounding in virtue and in grace, and to whom we gladly
refer all the blessings which England enjoys, all the pleasure we have
in our lives.

  Your Majesty’s most devoted servant,

  LONDON, 1628.

  To his very dear Friend, DOCTOR ARGENT, the excellent and
  accomplished President of the Royal College of Physicians, and to
  other learned Physicians, his most esteemed Colleagues.

I have already and repeatedly presented you, my learned friends, with
my new views of the motion and function of the heart, in my anatomical
lectures; but having now for nine years and more confirmed these views
by multiplied demonstrations in your presence, illustrated them by
arguments, and freed them from the objections of the most learned and
skilful anatomists, I at length yield to the requests, I might say
entreaties, of many, and here present them for general consideration in
this treatise.

Were not the work indeed presented through you, my learned friends,
I should scarce hope that it could come out scatheless and complete;
for you have in general been the faithful witnesses of almost all the
instances from which I have either collected the truth or confuted
error; you have seen my dissections, and at my demonstrations of all
that I maintain to be objects of sense, you have been accustomed to
stand by and bear me out with your testimony. And as this book alone
declares the blood to course and revolve by a new route, very different
from the ancient and beaten pathway trodden for so many ages, and
illustrated by such a host of learned and distinguished men, I was
greatly afraid lest I might be charged with presumption did I lay my
work before the public at home, or send it beyond seas for impression,
unless I had first proposed its subject to you, had confirmed its
conclusions by ocular demonstrations in your presence, had replied
to your doubts and objections, and secured the assent and support of
our distinguished President. For I was most intimately persuaded,
that if I could make good my proposition before you and our College,
illustrious by its numerous body of learned individuals, I had less
to fear from others; I even ventured to hope that I should have the
comfort of finding all that you had granted me in your sheer love of
truth, conceded by others who were philosophers like yourselves. For
true philosophers, who are only eager for truth and knowledge, never
regard themselves as already so thoroughly informed, but that they
welcome further information from whomsoever and from whencesoever it
may come; nor are they so narrow-minded as to imagine any of the arts
or sciences transmitted to us by the ancients, in such a state of
forwardness or completeness, that nothing is left for the ingenuity and
industry of others; very many, on the contrary, maintain that all we
know is still infinitely less than all that still remains unknown; nor
do philosophers pin their faith to others’ precepts in such wise that
they lose their liberty, and cease to give credence to the conclusions
of their proper senses. Neither do they swear such fealty to their
mistress Antiquity, that they openly, and in sight of all, deny and
desert their friend Truth. But even as they see that the credulous
and vain are disposed at the first blush to accept and to believe
everything that is proposed to them, so do they observe that the dull
and unintellectual are indisposed to see what lies before their eyes,
and even to deny the light of the noonday sun. They teach us in our
course of philosophy as sedulously to avoid the fables of the poets and
the fancies of the vulgar, as the false conclusions of the sceptics.
And then the studious, and good, and true, never suffer their minds
to be warped by the passions of hatred and envy, which unfit men duly
to weigh the arguments that are advanced in behalf of truth, or to
appreciate the proposition that is even fairly demonstrated; neither
do they think it unworthy of them to change their opinion if truth
and undoubted demonstration require them so to do; nor do they esteem
it discreditable to desert error, though sanctioned by the highest
antiquity; for they know full well that to err, to be deceived, is
human; that many things are discovered by accident, and that many may
be learned indifferently from any quarter, by an old man from a youth,
by a person of understanding from one of inferior capacity.

My dear colleagues, I had no purpose to swell this treatise into a
large volume by quoting the names and writings of anatomists, or to
make a parade of the strength of my memory, the extent of my reading,
and the amount of my pains; because I profess both to learn and to
teach anatomy, not from books but from dissections; not from the
positions of philosophers but from the fabric of nature; and then
because I do not think it right or proper to strive to take from the
ancients any honour that is their due, nor yet to dispute with the
moderns, and enter into controversy with those who have excelled in
anatomy and been my teachers, I would not charge with wilful falsehood
any one who was sincerely anxious for truth, nor lay it to any one’s
door as a crime that he had fallen into error. I avow myself the
partisan of truth alone; and I can indeed say that I have used all my
endeavours, bestowed all my pains on an attempt to produce something
that should be agreeable to the good, profitable to the learned, and
useful to letters.

  Farewell, most worthy Doctors,
  And think kindly of your Anatomist,





As we are about to discuss the motion, action, and use of the heart
and arteries, it is imperative on us first to state what has been
thought of these things by others in their writings, and what has been
held by the vulgar and by tradition, in order that what is true may
be confirmed, and what is false set right by dissection, multiplied
experience, and accurate observation.

Almost all anatomists, physicians, and philosophers, up to the present
time, have supposed, with Galen, that the object of the pulse was the
same as that of respiration, and only differed in one particular,
this being conceived to depend on the animal, the respiration on the
vital faculty; the two, in all other respects, whether with reference
to purpose or to motion, comporting themselves alike. Whence it is
affirmed, as by Hieronymus Fabricius of Aquapendente, in his book
on “Respiration,” which has lately appeared, that as the pulsation
of the heart and arteries does not suffice for the ventilation and
refrigeration of the blood, therefore were the lungs fashioned to
surround the heart. From this it appears, that whatever has hitherto
been said upon the systole and diastole, on the motion of the heart
and arteries, has been said with especial reference to the lungs.

But as the structure and movements of the heart differ from those of
the lungs, and the motions of the arteries from those of the chest, so
seems it likely that other ends and offices will thence arise, and that
the pulsations and uses of the heart, likewise of the arteries, will
differ in many respects from the heavings and uses of the chest and
lungs. For did the arterial pulse and the respiration serve the same
ends; did the arteries in their diastole take air into their cavities,
as commonly stated, and in their systole emit fuliginous vapours by
the same pores of the flesh and skin; and further, did they, in the
time intermediate between the diastole and the systole, contain air,
and at all times either air, or spirits, or fuliginous vapours, what
should then be said to Galen, who wrote a book on purpose to show
that by nature the arteries contained blood, and nothing but blood;
neither spirits nor air, consequently, as may be readily gathered from
the experiments and reasonings contained in the same book? Now if the
arteries are filled in the diastole with air then taken into them (a
larger quantity of air penetrating when the pulse is large and full),
it must come to pass, that if you plunge into a bath of water or of
oil when the pulse is strong and full, it ought forthwith to become
either smaller or much slower, since the circumambient bath will render
it either difficult or impossible for the air to penetrate. In like
manner, as all the arteries, those that are deep-seated as well as
those that are superficial, are dilated at the same instant, and with
the same rapidity, how were it possible that air should penetrate to
the deeper parts as freely and quickly through the skin, flesh, and
other structures, as through the mere cuticle? And how should the
arteries of the fœtus draw air into their cavities through the abdomen
of the mother and the body of the womb? And how should seals, whales,
dolphins, and other cetaceans, and fishes of every description, living
in the depths of the sea, take in and emit air by the diastole and
systole of their arteries through the infinite mass of waters? For to
say that they absorb the air that is infixed in the water, and emit
their fumes into this medium, were to utter something very like a mere
figment. And if the arteries in their systole expel fuliginous vapours
from their cavities through the pores of the flesh and skin, why not
the spirits, which are said to be contained in these vessels, at the
same time, since spirits are much more subtile than fuliginous vapours
or smoke? And further, if the arteries take in and cast out air in the
systole and diastole, like the lungs in the process of respiration,
wherefore do they not do the same thing when a wound is made in one of
them, as is done in the operation of arteriotomy? When the windpipe is
divided, it is sufficiently obvious that the air enters and returns
through the wound by two opposite movements; but when an artery is
divided, it is equally manifest that blood escapes in one continuous
stream, and that no air either enters or issues. If the pulsations
of the arteries fan and refrigerate the several parts of the body as
the lungs do the heart, how comes it, as is commonly said, that the
arteries carry the vital blood into the different parts, abundantly
charged with vital spirits, which cherish the heat of these parts,
sustain them when asleep, and recruit them when exhausted? and how
should it happen that, if you tie the arteries, immediately the parts
not only become torpid, and frigid, and look pale, but at length cease
even to be nourished? This, according to Galen, is because they are
deprived of the heat which flowed through all parts from the heart,
as its source; whence it would appear that the arteries rather carry
warmth to the parts than serve for any fanning or refrigeration.
Besides, how can the diastole [of the arteries] draw spirits from the
heart to warm the body and its parts, and, from without, means of
cooling or tempering them? Still further, although some affirm that
the lungs, arteries, and heart have all the same offices, they yet
maintain that the heart is the workshop of the spirits, and that the
arteries contain and transmit them; denying, however, in opposition
to the opinion of Columbus, that the lungs can either make or contain
spirits; and then they assert, with Galen, against Erasistratus, that
it is blood, not spirits, which is contained in the arteries.

These various opinions are seen to be so incongruous and mutually
subversive, that every one of them is not unjustly brought under
suspicion. That it is blood and blood alone which is contained in the
arteries is made manifest by the experiment of Galen, by arteriotomy,
and by wounds; for from a single artery divided, as Galen himself
affirms in more than one place, the whole of the blood may be withdrawn
in the course of half an hour, or less. The experiment of Galen
alluded to is this: “If you include a portion of an artery between
two ligatures, and slit it open lengthways, you will find nothing but
blood;” and thus he proves that the arteries contain blood only. And
we too may be permitted to proceed by a like train of reasoning: if we
find the same blood in the arteries that we find in the veins, which
we have tied in the same way, as I have myself repeatedly ascertained,
both in the dead body and in living animals, we may fairly conclude
that the arteries contain the same blood as the veins, and nothing but
the same blood. Some, whilst they attempt to lessen the difficulty
here, affirming that the blood is spirituous and arterious, virtually
concede that the office of the arteries is to carry blood from the
heart into the whole of the body, and that they are therefore filled
with blood; for spirituous blood is not the less blood on that account.
And then no one denies that the blood as such, even the portion of it
which flows in the veins, is imbued with spirits. But if that portion
which is contained in the arteries be richer in spirits, it is still
to be believed that these spirits are inseparable from the blood, like
those in the veins: that the blood and spirits constitute one body
(like whey and butter in milk, or heat [and water] in hot water), with
which the arteries are charged, and for the distribution of which from
the heart they are provided, and that this body is nothing else than
blood. But if this blood be said to be drawn from the heart into the
arteries by the diastole of these vessels, it is then assumed that the
arteries by their distension are filled with blood, and not with the
ambient air, as heretofore; for if they be said also to become filled
with air from the ambient atmosphere, how and when, I ask, can they
receive blood from the heart? If it be answered: during the systole; I
say, that seems impossible; the arteries would then have to fill whilst
they contracted; in other words, to fill, and yet not become distended.
But if it be said: during the diastole, they would then, and for two
opposite purposes, be receiving both blood and air, and heat and cold;
which is improbable. Further, when it is affirmed that the diastole of
the heart and arteries is simultaneous, and the systole of the two is
also concurrent, there is another incongruity. For how can two bodies
mutually connected, which are simultaneously distended, attract or
draw anything from one another; or, being simultaneously contracted,
receive anything from each other? And then, it seems impossible that
one body can thus attract another body into itself, so as to become
distended, seeing that to be distended is to be passive, unless, in the
manner of a sponge, previously compressed by an external force, whilst
it is returning to its natural state. But it is difficult to conceive
that there can be anything of this kind in the arteries. The arteries
dilate, because they are filled like bladders or leathern bottles; they
are not filled because they expand like bellows. This I think easy
of demonstration; and indeed conceive that I have already proved it.
Nevertheless, in that book of Galen headed “Quod Sanguis continetur in
Arteriis,” he quotes an experiment to prove the contrary: An artery
having been exposed, is opened longitudinally, and a reed or other
pervious tube, by which the blood is prevented from being lost, and the
wound is closed, is inserted into the vessel through the opening. “So
long,” he says, “as things are thus arranged, the whole artery will
pulsate; but if you now throw a ligature about the vessel and tightly
compress its tunics over the tube, you will no longer see the artery
beating beyond the ligature.” I have never performed this experiment
of Galen’s, nor do I think that it could very well be performed in the
living body, on account of the profuse flow of blood that would take
place from the vessel which was operated on; neither would the tube
effectually close the wound in the vessel without a ligature; and I
cannot doubt but that the blood would be found to flow out between the
tube and the vessel. Still Galen appears by this experiment to prove
both that the pulsative faculty extends from the heart by the walls of
the arteries, and that the arteries, whilst they dilate, are filled
by that pulsific force, because they expand like bellows, and do not
dilate because they are filled like skins. But the contrary is obvious
in arteriotomy and in wounds; for the blood spurting from the arteries
escapes with force, now farther, now not so far, alternately, or in
jets; and the jet always takes place with the diastole of the artery,
never with the systole. By which it clearly appears that the artery is
dilated by the impulse of the blood; for of itself it would not throw
the blood to such a distance, and whilst it was dilating; it ought
rather to draw air into its cavity through the wound, were those things
true that are commonly stated concerning the uses of the arteries. Nor
let the thickness of the arterial tunics impose upon us, and lead us
to conclude that the pulsative property proceeds along them from the
heart. For in several animals the arteries do not apparently differ
from the veins; and in extreme parts of the body, where the arteries
are minutely subdivided, as in the brain, the hand, &c., no one could
distinguish the arteries from the veins by the dissimilar characters of
their coats; the tunics of both are identical. And then, in an aneurism
proceeding from a wounded or eroded artery, the pulsation is precisely
the same as in the other arteries, and yet it has no proper arterial
tunic. This the learned Riolanus testifies to, along with me, in his
Seventh Book.

Nor let any one imagine that the uses of the pulse and the respiration
are the same, because under the influence of the same causes, such as
running, anger, the warm bath, or any other heating thing, as Galen
says, they become more frequent and forcible together. For, not only
is experience in opposition to this idea, though Galen endeavours to
explain it away, when we see that with excessive repletion the pulse
beats more forcibly, whilst the respiration is diminished in amount;
but in young persons the pulse is quick, whilst respiration is slow.
So is it also in alarm, and amidst care, and under anxiety of mind;
sometimes, too, in fevers, the pulse is rapid, but the respiration is
slower than usual.

These and other objections of the same kind may be urged against the
opinions mentioned. Nor are the views that are entertained of the
offices and pulse of the heart, perhaps, less bound up with great
and most inextricable difficulties. The heart, it is vulgarly said,
is the fountain and workshop of the vital spirits, the centre from
whence life is dispensed to the several parts of the body; and yet
it is denied that the right ventricle makes spirits; it is rather
held to supply nourishment to the lungs; whence it is maintained that
fishes are without any right ventricle (and indeed every animal wants
a right ventricle which is unfurnished with lungs), and that the right
ventricle is present solely for the sake of the lungs.

1. Why, I ask, when we see that the structure of both ventricles is
almost identical, there being the same apparatus of fibres, and
braces, and valves, and vessels, and auricles, and in both the same
infarction of blood, in the subjects of our dissections, of the like
black colour, and coagulated--why, I say, should their uses be imagined
to be different, when the action, motion, and pulse of both are the
same? If the three tricuspid valves placed at the entrance into the
right ventricle prove obstacles to the reflux of the blood into the
vena cava, and if the three semilunar valves which are situated at the
commencement of the pulmonary artery be there, that they may prevent
the return of the blood into the ventricle; wherefore, when we find
similar structures in connexion with the left ventricle, should we deny
that they are there for the same end, of preventing here the egress,
there the regurgitation of the blood?

2. And again, when we see that these structures, in point of size,
form, and situation, are almost in every respect the same in the left
as in the right ventricle, wherefore should it be maintained that
things are here arranged in connexion with the egress and regress of
spirits, there, i.e. in the right, of blood? The same arrangement
cannot be held fitted to favour or impede the motion of blood and of
spirits indifferently.

3. And when we observe that the passages and vessels are severally in
relation to one another in point of size, viz., the pulmonary artery to
the pulmonary veins; wherefore should the one be imagined destined to a
private or particular purpose, that, to wit, of nourishing the lungs,
the other to a public and general function?

4. And, as Realdus Columbus says, how can it be conceived that such a
quantity of blood should be required for the nutrition of the lungs;
the vessel that leads to them, the vena arteriosa or pulmonary artery
being of greater capacity than both the iliac veins?

5. And I ask further: as the lungs are so close at hand, and in
continual motion, and the vessel that supplies them is of such
dimensions, what is the use or meaning of the pulse of the right
ventricle? and why was nature reduced to the necessity of adding
another ventricle for the sole purpose of nourishing the lungs?

When it is said that the left ventricle obtains materials for the
formation of spirits, air to wit, and blood, from the lungs and right
sinuses of the heart, and in like manner sends spirituous blood into
the aorta, drawing fuliginous vapours from thence, and sending them
by the arteria venosa into the lungs, whence spirits are at the same
time obtained for transmission into the aorta, I ask how, and by what
means, is the separation effected? and how comes it that spirits and
fuliginous vapours can pass hither and thither without admixture or
confusion. If the mitral cuspidate valves do not prevent the egress of
fuliginous vapours to the lungs, how should they oppose the escape of
air? and how should the semilunars hinder the regress of spirits from
the aorta upon each supervening diastole of the heart? and, above all,
how can they say that the spirituous blood is sent from the arteria
venalis (pulmonary veins) by the left ventricle into the lungs without
any obstacle to its passage from the mitral valves, when they have
previously asserted that the air entered by the same vessel from the
lungs into the left ventricle, and have brought forward these same
mitral valves as obstacles to its retrogression? Good God! how should
the mitral valves prevent regurgitation of air and not of blood?

Further, when they dedicate the vena arteriosa (or pulmonary artery), a
vessel of great size, and having the tunics of an artery, to none but
a kind of private and single purpose, that, namely, of nourishing the
lungs, why should the arteria venalis (or pulmonary vein), which is
scarcely of similar size, which has the coats of a vein, and is soft
and lax, be presumed to be made for many--three or four, different
uses? For they will have it that air passes through this vessel from
the lungs into the left ventricle; that fuliginous vapours escape by
it from the heart into the lungs; and that a portion of the spirituous
or spiritualized blood is distributed by it to the lungs for their

If they will have it that fumes and air--fumes flowing from, air
proceeding towards the heart--are transmitted by the same conduit, I
reply, that nature is not wont to institute but one vessel, to contrive
but one way for such contrary motions and purposes, nor is anything of
the kind seen elsewhere.

If fumes or fuliginous vapours and air permeate this vessel, as they do
the pulmonary bronchia, wherefore do we find neither air nor fuliginous
vapours when we divide the arteria venosa? why do we always find this
vessel full of sluggish blood, never of air? whilst in the lungs we
find abundance of air remaining.

If any one will perform Galen’s experiment of dividing the trachea of
a living dog, forcibly distending the lungs with a pair of bellows,
and then tying the trachea securely, he will find, when he has laid
open the thorax, abundance of air in the lungs, even to their extreme
investing tunic, but none in either the pulmonary veins, or left
ventricle of the heart. But did the heart either attract air from the
lungs, or did the lungs transmit any air to the heart, in the living
dog, by so much the more ought this to be the case in the experiment
just referred to. Who, indeed, doubts that, did he inflate the lungs
of a subject in the dissecting-room, he would instantly see the air
making its way by this route, were there actually any such passage for
it? But this office of the pulmonary veins, namely, the transference
of air from the lungs to the heart, is held of such importance, that
Hieronymus Fabricius, of Aquapendente, maintains the lungs were made
for the sake of this vessel, and that it constitutes the principal
element in their structure.

But I should like to be informed wherefore, if the pulmonary vein
were destined for the conveyance of air, it has the structure of a
blood-vessel here. Nature had rather need of annular tubes, such as
those of the bronchia, in order that they might always remain open, not
have been liable to collapse; and that they might continue entirely
free from blood, lest the liquid should interfere with the passage
of the air, as it so obviously does when the lungs labour from being
either greatly oppressed or loaded in a less degree with phlegm, as
they are when the breathing is performed with a sibilous or rattling

Still less is that opinion to be tolerated which (as a twofold matter,
one aëreal, one sanguineous, is required for the composition of vital
spirits,) supposes the blood to ooze through the septum of the heart
from the right to the left ventricle by certain secret pores, and
the air to be attracted from the lungs through the great vessel, the
pulmonary vein; and which will have it, consequently, that there are
numerous pores in the septum cordis adapted for the transmission of
the blood. But, in faith, no such pores can be demonstrated, neither
in fact do any such exist. For the septum of the heart is of a denser
and more compact structure than any portion of the body, except the
bones and sinews. But even supposing that there were foramina or pores
in this situation, how could one of the ventricles extract anything
from the other--the left, e.g., obtain blood from the right, when we
see that both ventricles contract and dilate simultaneously? Wherefore
should we not rather believe that the right took spirits from the left,
than that the left obtained blood from the right ventricle, through
these foramina? But it is certainly mysterious and incongruous that
blood should be supposed to be most commodiously drawn through a set of
obscure or invisible pores, and air through perfectly open passages,
at one and the same moment. And why, I ask, is recourse had to secret
and invisible porosities, to uncertain and obscure channels, to explain
the passage of the blood into the left ventricle, when there is so
open a way through the pulmonary veins? I own it has always appeared
extraordinary to me that they should have chosen to make, or rather to
imagine, a way through the thick, hard, and extremely compact substance
of the septum cordis, rather than to take that by the open vas
venosum or pulmonary vein, or even through the lax, soft, and spongy
substance of the lungs at large. Besides, if the blood could permeate
the substance of the septum, or could be imbibed from the ventricles,
what use were there for the coronary artery and vein, branches of
which proceed to the septum itself, to supply it with nourishment? And
what is especially worthy of notice is this: if in the fœtus, where
everything is more lax and soft, nature saw herself reduced to the
necessity of bringing the blood from the right into the left side of
the heart by the foramen ovale, from the vena cava through the arteria
venosa, how should it be likely that in the adult she should pass it so
commodiously, and without an effort, through the septum ventriculorum,
which has now become denser by age?

Andreas Laurentius,[18] resting on the authority of Galen[19] and the
experience of Hollerius, asserts and proves that the serum and pus in
empyema, absorbed from the cavities of the chest into the pulmonary
vein, may be expelled and got rid of with the urine and fæces through
the left ventricle of the heart and arteries. He quotes the case of
a certain person affected with melancholia, and who suffered from
repeated fainting fits, who was relieved from the paroxysms on passing
a quantity of turbid, fetid, and acrid urine; but he died at last, worn
out by the disease; and when the body came to be opened after death, no
fluid like that he had micturated was discovered either in the bladder
or in the kidneys; but in the left ventricle of the heart and cavity
of the thorax plenty of it was met with; and then Laurentius boasts
that he had predicted the cause of the symptoms. For my own part,
however, I cannot but wonder, since he had divined and predicted that
heterogeneous matter could be discharged by the course he indicates,
why he could not or would not perceive, and inform us that, in the
natural state of things, the blood might be commodiously transferred
from the lungs to the left ventricle of the heart by the very same

  [18] Lib. ix, cap. xi, quest. 12.

  [19] De Locis Affectis., lib. vi, cap. 7.

Since, therefore, from the foregoing considerations and many others
to the same effect, it is plain that what has heretofore been said
concerning the motion and function of the heart and arteries must
appear obscure, or inconsistent or even impossible to him who carefully
considers the entire subject; it will be proper to look more narrowly
into the matter; to contemplate the motion of the heart and arteries,
not only in man, but in all animals that have hearts; and further, by
frequent appeals to vivisection, and constant ocular inspection, to
investigate and endeavour to find the truth.



When I first gave my mind to vivisections, as a means of discovering
the motions and uses of the heart, and sought to discover these from
actual inspection, and not from the writings of others, I found the
task so truly arduous, so full of difficulties, that I was almost
tempted to think, with Fracastorius, that the motion of the heart was
only to be comprehended by God. For I could neither rightly perceive at
first when the systole and when the diastole took place, nor when and
where dilatation and contraction occurred, by reason of the rapidity of
the motion, which in many animals is accomplished in the twinkling of
an eye, coming and going like a flash of lightning; so that the systole
presented itself to me now from this point, now from that; the diastole
the same; and then everything was reversed, the motions occurring, as
it seemed, variously and confusedly together. My mind was therefore
greatly unsettled, nor did I know what I should myself conclude, nor
what believe from others; I was not surprised that Andreas Laurentius
should have said that the motion of the heart was as perplexing as the
flux and reflux of Euripus had appeared to Aristotle.

At length, and by using greater and daily diligence, having frequent
recourse to vivisections, employing a variety of animals for the
purpose, and collating numerous observations, I thought that I had
attained to the truth, that I should extricate myself and escape from
this labyrinth, and that I had discovered what I so much desired, both
the motion and the use of the heart and arteries; since which time I
have not hesitated to expose my views upon these subjects, not only in
private to my friends, but also in public, in my anatomical lectures,
after the manner of the Academy of old.

These views, as usual, pleased some more, others less; some chid and
calumniated me, and laid it to me as a crime that I had dared to
depart from the precepts and opinion of all anatomists; others desired
further explanations of the novelties, which they said were both worthy
of consideration, and might perchance be found of signal use. At
length, yielding to the requests of my friends, that all might be made
participators in my labours, and partly moved by the envy of others,
who receiving my views with uncandid minds and understanding them
indifferently, have essayed to traduce me publicly, I have been moved
to commit these things to the press, in order that all may be enabled
to form an opinion both of me and my labours. This step I take all
the more willingly, seeing that Hieronymus Fabricius of Aquapendente,
although he has accurately and learnedly delineated almost every one
of the several parts of animals in a special work, has left the heart
alone untouched. Finally, if any use or benefit to this department
of the republic of letters should accrue from my labours, it will,
perhaps, be allowed that I have not lived idly, and, as the old man in
the comedy says:

  For never yet has any one attained
  To such perfection, but that time, and place,
  And use, have brought addition to his knowledge;
  Or made correction, or admonished him,
  That he was ignorant of much which he
  Had thought he knew; or led him to reject
  What he had once esteemed of highest price.

So will it, perchance, be found with reference to the heart at this
time; or others, at least, starting from hence, the way pointed out
to them, advancing under the guidance of a happier genius, may make
occasion to proceed more fortunately, and to inquire more accurately.



In the first place, then, when the chest of a living animal is laid
open and the capsule that immediately surrounds the heart is slit up or
removed, the organ is seen now to move, now to be at rest;--there is a
time when it moves, and a time when it is motionless.

These things are more obvious in the colder animals, such as toads,
frogs, serpents, small fishes, crabs, shrimps, snails, and shell-fish.
They also become more distinct in warm-blooded animals, such as the dog
and hog, if they be attentively noted when the heart begins to flag, to
move more slowly, and, as it were, to die: the movements then become
slower and rarer, the pauses longer, by which it is made much more
easy to perceive and unravel what the motions really are, and how they
are performed. In the pause, as in death, the heart is soft, flaccid,
exhausted, lying, as it were, at rest.

In the motion, and interval in which this is accomplished, three
principal circumstances are to be noted:

1. That the heart is erected, and rises upwards to a point, so that
at this time it strikes against the breast and the pulse is felt

2. That it is everywhere contracted, but more especially towards
the sides, so that it looks narrower, relatively longer, more drawn
together. The heart of an eel taken out of the body of the animal and
placed upon the table or the hand, shows these particulars; but the
same things are manifest in the heart of small fishes and of those
colder animals where the organ is more conical or elongated.

3. The heart being grasped in the hand, is felt to become harder during
its action. Now this hardness proceeds from tension, precisely as when
the forearm is grasped, its tendons are perceived to become tense and
resilient when the fingers are moved.

4. It may further be observed in fishes, and the colder blooded
animals, such as frogs, serpents, &c., that the heart, when it moves,
becomes of a paler colour, when quiescent of a deeper blood-red colour.

From these particulars it appeared evident to me that the motion of
the heart consists in a certain universal tension--both contraction in
the line of its fibres, and constriction in every sense. It becomes
erect, hard, and of diminished size during its action; the motion is
plainly of the same nature as that of the muscles when they contract in
the line of their sinews and fibres; for the muscles, when in action,
acquire vigour and tenseness, and from soft become hard, prominent, and
thickened: in the same manner the heart.

We are therefore authorized to conclude that the heart, at the moment
of its action, is at once constricted on all sides, rendered thicker in
its parietes and smaller in its ventricles, and so made apt to project
or expel its charge of blood. This, indeed, is made sufficiently
manifest by the fourth observation preceding, in which we have seen
that the heart, by squeezing out the blood it contains becomes paler,
and then when it sinks into repose and the ventricle is filled anew
with blood, that the deeper crimson colour returns. But no one need
remain in doubt of the fact, for if the ventricle be pierced the blood
will be seen to be forcibly projected outwards upon each motion or
pulsation when the heart is tense.

These things, therefore, happen together or at the same instant: the
tension of the heart, the pulse of its apex, which is felt externally
by its striking against the chest, the thickening of its parietes, and
the forcible expulsion of the blood it contains by the constriction of
its ventricles.

Hence the very opposite of the opinions commonly received, appears
to be true; inasmuch as it is generally believed that when the heart
strikes the breast and the pulse is felt without, the heart is dilated
in its ventricles and is filled with blood; but the contrary of this is
the fact, and the heart, when it contracts [and the shock is given], is
emptied. Whence the motion which is generally regarded as the diastole
of the heart, is in truth its systole. And in like manner the intrinsic
motion of the heart is not the diastole but the systole; neither is
it in the diastole that the heart grows firm and tense, but in the
systole, for then only, when tense, is it moved and made vigorous.

Neither is it by any means to be allowed that the heart only moves
in the line of its straight fibres, although the great Vesalius,
giving this notion countenance, quotes a bundle of osiers bound into a
pyramidal heap in illustration; meaning, that as the apex is approached
to the base, so are the sides made to bulge out in the fashion of
arches, the cavities to dilate, the ventricles to acquire the form of a
cupping-glass and so to suck in the blood. But the true effect of every
one of its fibres is to constringe the heart at the same time that
they render it tense; and this rather with the effect of thickening
and amplifying the walls and substance of the organ than enlarging its
ventricles. And, again, as the fibres run from the apex to the base,
and draw the apex towards the base, they do not tend to make the walls
of the heart bulge out in circles, but rather the contrary; inasmuch
as every fibre that is circularly disposed, tends to become straight
when it contracts; and is distended laterally and thickened, as in the
case of muscular fibres in general, when they contract, that is, when
they are shortened longitudinally, as we see them in the bellies of
the muscles of the body at large. To all this, let it be added, that
not only are the ventricles contracted in virtue of the direction
and condensation of their walls, but farther, that those fibres, or
bands, styled nerves by Aristotle, which are so conspicuous in the
ventricles of the larger animals, and contain all the straight fibres,
(the parietes of the heart containing only circular ones,) when they
contract simultaneously, by an admirable adjustment all the internal
surfaces are drawn together, as if with cords, and so is the charge of
blood expelled with force.

Neither is it true, as vulgarly believed, that the heart by any
dilatation or motion of its own has the power of drawing the blood
into the ventricles; for when it acts and becomes tense, the blood is
expelled; when it relaxes and sinks together it receives the blood in
the manner and wise which will by and by be explained.



In connection with the motions of the heart these things are further to
be observed having reference to the motions and pulses of the arteries:

1. At the moment the heart contracts, and when the breast is struck,
when in short the organ is in its state of systole, the arteries are
dilated, yield a pulse, and are in the state of diastole. In like
manner, when the right ventricle contracts and propels its charge of
blood, the arterial vein [the pulmonary artery] is distended at the
same time with the other arteries of the body.

2. When the left ventricle ceases to act, to contract, to pulsate,
the pulse in the arteries also ceases; further, when this ventricle
contracts languidly, the pulse in the arteries is scarcely perceptible.
In like manner, the pulse in the right ventricle failing, the pulse in
the vena arteriosa [pulmonary artery] ceases also.

3. Further, when an artery is divided or punctured, the blood is
seen to be forcibly propelled from the wound at the moment the left
ventricle contracts; and, again, when the pulmonary artery is wounded,
the blood will be seen spouting forth with violence at the instant when
the right ventricle contracts.

So also in fishes, if the vessel which leads from the heart to the
gills be divided, at the moment when the heart becomes tense and
contracted, at the same moment does the blood flow with force from the
divided vessel.

In the same way, finally, when we see the blood in arteriotomy
projected now to a greater, now to a less distance, and that the
greater jet corresponds to the diastole of the artery and to the time
when the heart contracts and strikes the ribs, and is in its state of
systole, we understand that the blood is expelled by the same movement.

From these facts it is manifest, in opposition to commonly received
opinions, that the diastole of the arteries corresponds with the time
of the heart’s systole; and that the arteries are filled and distended
by the blood forced into them by the contraction of the ventricles; the
arteries, therefore, are distended, because they are filled like sacs
or bladders, and are not filled because they expand like bellows. It is
in virtue of one and the same cause, therefore, that all the arteries
of the body pulsate, viz. the contraction of the left ventricle; in the
same way as the pulmonary artery pulsates by the contraction of the
right ventricle.

Finally, that the pulses of the arteries are due to the impulses of the
blood from the left ventricle, may be illustrated by blowing into a
glove, when the whole of the fingers will be found to become distended
at one and the same time, and in their tension to bear some resemblance
to the pulse. For in the ratio of the tension is the pulse of the
heart, fuller, stronger, more frequent as that acts more vigorously,
still preserving the rhythm and volume and order of the heart’s
contractions. Nor is it to be expected that because of the motion of
the blood, the time at which the contraction of the heart takes place,
and that at which the pulse in an artery (especially a distant one)
is felt, shall be otherwise than simultaneous: it is here the same
as in blowing up a glove or bladder; for in a plenum (as in a drum,
a long piece of timber, &c.) the stroke and the motion occur at both
extremities at the same time. Aristotle,[20] too, has said, “the blood
of all animals palpitates within their veins, (meaning the arteries,)
and by the pulse is sent everywhere simultaneously.” And further,[21]
“thus do all the veins pulsate together and by successive strokes,
because they all depend upon the heart; and, as it is always in
motion, so are they likewise always moving together, but by successive
movements.” It is well to observe with Galen, in this place, that the
old philosophers called the arteries veins.

  [20] De Animal. iii, cap. 9.

  [21] De Respirat. cap. 20.

I happened upon one occasion to have a particular case under my care,
which plainly satisfied me of this truth: A certain person was affected
with a large pulsating tumour on the right side of the neck, called an
aneurism, just at that part where the artery descends into the axilla,
produced by an erosion of the artery itself, and daily increasing in
size; this tumour was visibly distended as it received the charge of
blood brought to it by the artery, with each stroke of the heart: the
connexion of parts was obvious when the body of the patient came to be
opened after his death. The pulse in the corresponding arm was small,
in consequence of the greater portion of the blood being diverted into
the tumour and so intercepted.

Whence it appears that wherever the motion of the blood through the
arteries is impeded, whether it be by compression or infarction, or
interception, there do the remote divisions of the arteries beat less
forcibly, seeing that the pulse of the arteries is nothing more than
the impulse or shock of the blood in these vessels.



Besides the motions already spoken of, we have still to consider those
that appertain to the auricles.

Casper Bauhin and John Riolan,[22] most learned men and skilful
anatomists, inform us from their observations, that if we carefully
watch the movements of the heart in the vivisection of an animal, we
shall perceive four motions distinct in time and in place, two of which
are proper to the auricles, two to the ventricles. With all deference
to such authority I say, that there are four motions distinct in point
of place, but not of time; for the two auricles move together, and so
also do the two ventricles, in such wise that though the places be
four, the times are only two. And this occurs in the following manner:

  [22] Bauhin, lib. ii, cap. 21. Riolan, lib. viii, cap. 1.

There are, as it were, two motions going on together: one of the
auricles, another of the ventricles; these by no means taking place
simultaneously, but the motion of the auricles preceding, that of the
heart itself following; the motion appearing to begin from the auricles
and to extend to the ventricles. When all things are becoming languid,
and the heart is dying, as also in fishes and the colder blooded
animals, there is a short pause between these two motions, so that the
heart aroused, as it were, appears to respond to the motion, now more
quickly, now more tardily; and at length, and when near to death, it
ceases to respond by its proper motion, but seems, as it were, to nod
the head, and is so obscurely moved that it appears rather to give
signs of motion to the pulsating auricle, than actually to move. The
heart, therefore, ceases to pulsate sooner than the auricles, so that
the auricles have been said to outlive it, the left ventricle ceasing
to pulsate first of all; then its auricle, next the right ventricle;
and, finally, all the other parts being at rest and dead, as Galen
long since observed, the right auricle still continues to beat; life,
therefore, appears to linger longest in the right auricle. Whilst the
heart is gradually dying, it is sometimes seen to reply, after two or
three contractions of the auricles, roused as it were to action, and
making a single pulsation, slowly, unwillingly, and with an effort.

But this especially is to be noted, that after the heart has ceased
to beat, the auricles however still contracting, a finger placed upon
the ventricles perceives the several pulsations of the auricles,
precisely in the same way and for the same reason, as we have said,
that the pulses of the ventricles are felt in the arteries, to wit,
the distension produced by the jet of blood. And if at this time, the
auricles alone pulsating, the point of the heart be cut off with a
pair of scissors, you will perceive the blood flowing out upon each
contraction of the auricles. Whence it is manifest how the blood enters
the ventricles, not by any attraction or dilatation of the heart, but
thrown into them by the pulses of the auricles.

And here I would observe, that whenever I speak of pulsations as
occurring in the auricles or ventricles, I mean contractions: first
the auricles _contract_, and then and subsequently the heart itself
_contracts_. When the auricles contract they are seen to become whiter,
especially where they contain but little blood; but they are filled as
magazines or reservoirs of the blood, which is tending spontaneously
and, by the motion of the veins, under pressure towards the centre;
the whiteness indicated is most conspicuous towards the extremities or
edges of the auricles at the time of their contractions.

In fishes and frogs, and other animals which have hearts with but
a single ventricle, and for an auricle have a kind of bladder much
distended with blood, at the base of the organ, you may very plainly
perceive this bladder contracting first, and the contraction of the
heart or ventricle following afterwards.

But I think it right to describe what I have observed of an opposite
character: the heart of an eel, of several fishes, and even of some [of
the higher] animals taken out of the body, beats without auricles; nay,
if it be cut in pieces the several parts may still be seen contracting
and relaxing; so that in these creatures the body of the heart may be
seen pulsating, palpitating, after the cessation of all motion in the
auricle. But is not this perchance peculiar to animals more tenacious
of life, whose radical moisture is more glutinous, or fat and sluggish,
and less readily soluble? The same faculty indeed appears in the flesh
of eels, generally, which even when skinned and embowelled, and cut
into pieces, are still seen to move.

Experimenting with a pigeon upon one occasion, after the heart had
wholly ceased to pulsate, and the auricles too had become motionless,
I kept my finger wetted with saliva and warm for a short time upon the
heart, and observed, that under the influence of this fomentation it
recovered new strength and life, so that both ventricles and auricles
pulsated, contracting and relaxing alternately, recalled as it were
from death to life.

Besides this, however, I have occasionally observed, after the heart
and even its right auricle had ceased pulsating,--when it was in
articulo mortis in short,--that an obscure motion, an undulation or
palpitation, remained in the blood itself, which was contained in the
right auricle, this being apparent so long as it was imbued with heat
and spirit. And indeed a circumstance of the same kind is extremely
manifest in the course of the generation of animals, as may be seen in
the course of the first seven days of the incubation of the chick: A
drop of blood makes its appearance which palpitates, as Aristotle had
already observed; from this, when the growth is further advanced and
the chick is fashioned, the auricles of the heart are formed, which
pulsating henceforth give constant signs of life. When at length, and
after the lapse of a few days, the outline of the body begins to be
distinguished, then is the ventricular part of the heart also produced;
but it continues for a time white and apparently bloodless, like the
rest of the animal; neither does it pulsate or give signs of motion. I
have seen a similar condition of the heart in the human foetus about
the beginning of the third month, the heart being then whitish and
bloodless, although its auricles contained a considerable quantity of
purple blood. In the same way in the egg, when the chick was formed and
had increased in size, the heart too increased and acquired ventricles,
which then began to receive and to transmit blood.

And this leads me to remark, that he who inquires very particularly
into this matter will not conclude that the heart, as a whole, is
the primum vivens, ultimum moriens--the first part to live, the last
to die, but rather its auricles, or the part which corresponds to
the auricles in serpents, fishes, &c., which both lives before the
heart[23] and dies after it.

  [23] [The reader will observe that Harvey, when he speaks of the
  _heart_, always means the ventricles or ventricular portion of the

Nay, has not the blood itself or spirit an obscure palpitation inherent
in it, which it has even appeared to me to retain after death? and it
seems very questionable whether or not we are to say that life begins
with the palpitation or beating of the heart. The seminal fluid of
all animals--the prolific spirit, as Aristotle observed, leaves their
body with a bound and like a living thing; and nature in death, as
Aristotle[24] further remarks, retracing her steps, reverts to whence
she had set out, returns at the end of her course to the goal whence
she had started; and as animal generation proceeds from that which is
not animal, entity from non-entity, so, by a retrograde course, entity,
by corruption, is resolved into non-entity; whence that in animals,
which was last created, fails first; and that which was first, fails

  [24] De Motu Animal. cap. 8.

I have also observed, that almost all animals have truly a heart, not
the larger creatures only, and those that have red blood, but the
smaller, and [seemingly] bloodless ones also, such as slugs, snails,
scallops, shrimps, crabs, crayfish, and many others; nay, even in
wasps, hornets, and flies, I have, with the aid of a magnifying glass,
and at the upper part of what is called the tail, both seen the heart
pulsating myself, and shown it to many others.

But in the exsanguine tribes the heart pulsates sluggishly and
deliberately, contracting slowly as in animals that are moribund, a
fact that may readily be seen in the snail, whose heart will be found
at the bottom of that orifice in the right side of the body which is
seen to be opened and shut in the course of respiration, and whence
saliva is discharged, the incision being made in the upper aspect of
the body, near the part which corresponds to the liver.

This, however, is to be observed: that in winter and the colder season,
exsanguine animals, such as the snail, show no pulsations; they seem
rather to live after the manner of vegetables, or of those other
productions which are therefore designated plant-animals.

It is also to be noted that all animals which have a heart, have
also auricles, or something analogous to auricles; and further, that
wherever the heart has a double ventricle there are always two auricles
present, but not otherwise. If you turn to the production of the
chick in ovo, however, you will find at first no more than a vesicle
or auricle, or pulsating drop of blood; it is only by and by, when the
development has made some progress, that the heart is fashioned: even
so in certain animals not destined to attain to the highest perfection
in their organization, such as bees, wasps, snails, shrimps, crayfish,
&c., we only find a certain pulsating vesicle, like a sort of red or
white palpitating point, as the beginning or principle of their life.

We have a small shrimp in these countries, which is taken in the Thames
and in the sea, the whole of whose body is transparent; this creature,
placed in a little water, has frequently afforded myself and particular
friends an opportunity of observing the motions of the heart with the
greatest distinctness, the external parts of the body presenting no
obstacle to our view, but the heart being perceived as though it had
been seen through a window.

I have also observed the first rudiments of the chick in the course of
the fourth or fifth day of the incubation, in the guise of a little
cloud, the shell having been removed and the egg immersed in clear
tepid water. In the midst of the cloudlet in question there was a
bloody point so small that it disappeared during the contraction and
escaped the sight, but in the relaxation it reappeared again, red and
like the point of a pin; so that betwixt the visible and invisible,
betwixt being and not being, as it were, it gave by its pulses a kind
of representation of the commencement of life.[25]

  [25] [At the period Harvey indicates, a rudimentary auricle and
  ventricle exist, but are so transparent that unless with certain
  precautions their parietes cannot be seen. The filling and emptying
  of them, therefore, give the appearance of a speck of blood
  alternately appearing and disappearing.]



From these and other observations of the like kind, I am persuaded it
will be found that the motion of the heart is as follows:

First of all, the auricle contracts, and in the course of its
contraction throws the blood, (which it contains in ample quantity
as the head of the veins, the storehouse, and cistern of the blood,)
into the ventricle, which, being filled, the heart raises itself
straightway, makes all its fibres tense, contracts the ventricles, and
performs a beat, by which beat it immediately sends the blood supplied
to it by the auricle into the arteries; the right ventricle sending its
charge into the lungs by the vessel which is called vena arteriosa, but
which, in structure and function, and all things else, is an artery;
the left ventricle sending its charge into the aorta, and through this
by the arteries to the body at large.

These two motions, one of the ventricles, another of the auricles,
take place consecutively, but in such a manner that there is a kind
of harmony or rhythm preserved between them, the two concurring in
such wise that but one motion is apparent, especially in the warmer
blooded animals, in which the movements in question are rapid. Nor
is this for any other reason than it is in a piece of machinery, in
which, though one wheel gives motion to another, yet all the wheels
seem to move simultaneously; or in that mechanical contrivance which
is adapted to firearms, where the trigger being touched, down comes
the flint, strikes against the steel, elicits a spark, which falling
among the powder, it is ignited, upon which the flame extends, enters
the barrel, causes the explosion, propels the ball, and the mark is
attained--all of which incidents, by reason of the celerity with which
they happen, seem to take place in the twinkling of an eye. So also
in deglutition: by the elevation of the root of the tongue, and the
compression of the mouth, the food or drink is pushed into the fauces,
the larynx is closed by its own muscles, and the epiglottis, whilst the
pharynx, raised and opened by its muscles no otherwise than is a sac
that is to be filled, is lifted up, and its mouth dilated; upon which,
the mouthful being received, it is forced downwards by the transverse
muscles, and then carried farther by the longitudinal ones. Yet are
all these motions, though executed by different and distinct organs,
performed harmoniously, and in such order, that they seem to constitute
but a single motion and act, which we call deglutition.

Even so does it come to pass with the motions and action of the heart,
which constitute a kind of deglutition, a transfusion of the blood
from the veins to the arteries. And if any one, bearing these things
in mind, will carefully watch the motions of the heart in the body of
a living animal, he will perceive not only all the particulars I have
mentioned, viz. the heart becoming erect, and making one continuous
motion with its auricles; but farther, a certain obscure undulation
and lateral inclination in the direction of the axis of the right
ventricle, [the organ] twisting itself slightly in performing its work.
And indeed every one may see, when a horse drinks, that the water is
drawn in and transmitted to the stomach at each movement of the throat,
the motion being accompanied with a sound, and yielding a pulse both
to the ear and the touch; in the same way it is with each motion of
the heart, when there is the delivery of a quantity of blood from
the veins to the arteries, that a pulse takes place, and can be heard
within the chest.

The motion of the heart, then, is entirely of this description, and
the one action of the heart is the transmission of the blood and its
distribution, by means of the arteries, to the very extremities of the
body; so that the pulse which we feel in the arteries is nothing more
than the impulse of the blood derived from the heart.

Whether or not the heart, besides propelling the blood, giving it
motion locally, and distributing it to the body, adds anything else
to it,--heat, spirit, perfection,--must be inquired into by and by,
and decided upon other grounds. So much may suffice at this time, when
it is shown that by the action of the heart the blood is transfused
through the ventricles from the veins to the arteries, and distributed
by them to all parts of the body.

So much, indeed, is admitted by all [physiologists], both from the
structure of the heart and the arrangement and action of its valves.
But still they are like persons purblind or groping about in the dark;
and then they give utterence to diverse, contradictory, and incoherent
sentiments, delivering many things upon conjecture, as we have already
had occasion to remark.

The grand cause of hesitation and error in this subject appears to
me to have been the intimate connection between the heart and the
lungs. When men saw both the vena arteriosa [or pulmonary artery]
and the arteriæ venosæ [or pulmonary veins] losing themselves in the
lungs, of course it became a puzzle to them to know how or by what
means the right ventricle should distribute the blood to the body, or
the left draw it from the venæ cavæ. This fact is born witness to by
Galen, whose words, when writing against Erasistratus in regard to
the origin and use of the veins and the coction of the blood, are the
following:[26] “You will reply,” he says, “that the effect is so;
that the blood is prepared in the liver, and is thence transferred to
the heart to receive its proper form and last perfection; a statement
which does not appear devoid of reason; for no great and perfect work
is ever accomplished at a single effort, or receives its final polish
from one instrument. But if this be actually so, then show us another
vessel which draws the absolutely perfect blood from the heart, and
distributes it as the arteries do the spirits over the whole body.”
Here then is a reasonable opinion not allowed, because, forsooth,
besides not seeing the true means of transit, he could not discover the
vessel which should transmit the blood from the heart to the body at

  [26] De Placitis Hippocratis et Platonis, vi.

But had any one been there in behalf of Erasistratus, and of that
opinion which we now espouse, and which Galen himself acknowledges in
other respects consonant with reason, to have pointed to the aorta
as the vessel which distributes the blood from the heart to the rest
of the body, I wonder what would have been the answer of that most
ingenious and learned man? Had he said that the artery transmits
spirits and not blood, he would indeed sufficiently have answered
Erasistratus, who imagined that the arteries contained nothing but
spirits; but then he would have contradicted himself, and given a
foul denial to that for which he had keenly contended in his writings
against this very Erasistratus, to wit, that blood in substance
is contained in the arteries, and not spirits; a fact which he
demonstrated not only by many powerful arguments, but by experiments.

But if the divine Galen will here allow, as in other places he does,
“that all the arteries of the body arise from the great artery, and
that this takes its origin from the heart; that all these vessels
naturally contain and carry blood; that the three semilunar valves
situated at the orifice of the aorta prevent the return of the blood
into the heart, and that nature never connected them with this, the
most noble viscus of the body, unless for some most important end;”
if, I say, this father of physic admits all these things,--and I quote
his own words,--I do not see how he can deny that the great artery is
the very vessel to carry the blood, when it has attained its highest
term of perfection, from the heart for distribution to all parts of
the body. Or would he perchance still hesitate, like all who have
come after him, even to the present hour, because he did not perceive
the route by which the blood was transferred from the veins to the
arteries, in consequence, as I have already said, of the intimate
connexion between the heart and the lungs? And that this difficulty
puzzled anatomists not a little, when in their dissections they found
the pulmonary artery and left ventricle full of thick, black, and
clotted blood, plainly appears, when they felt themselves compelled
to affirm that the blood made its way from the right to the left
ventricle by sweating through the septum of the heart. But this I fancy
I have already refuted. A new pathway for the blood must therefore be
prepared and thrown open, and being once exposed, no further difficulty
will, I believe, be experienced by any one in admitting what I have
already proposed in regard to the pulse of the heart and arteries,
viz. the passage of the blood from the veins to the arteries, and its
distribution to the whole of the body by means of these vessels.



Since the intimate connexion of the heart with the lungs, which
is apparent in the human subject, has been the probable cause of
the errors that have been committed on this point, they plainly do
amiss who, pretending to speak of the parts of animals generally, as
anatomists for the most part do, confine their researches to the human
body alone, and that when it is dead. They obviously act no otherwise
than he who, having studied the forms of a single commonwealth, should
set about the composition of a general system of polity; or who, having
taken cognizance of the nature of a single field, should imagine that
he had mastered the science of agriculture; or who, upon the ground of
one particular proposition, should proceed to draw general conclusions.

Had anatomists only been as conversant with the dissection of the lower
animals as they are with that of the human body, the matters that have
hitherto kept them in a perplexity of doubt would, in my opinion, have
met them freed from every kind of difficulty.

And, first, in fishes, in which the heart consists of but a single
ventricle, they having no lungs, the thing is sufficiently manifest.
Here the sac, which is situated at the base of the heart, and is the
part analogous to the auricle in man, plainly throws the blood into the
heart, and the heart, in its turn, conspicuously transmits it by a
pipe or artery, or vessel analogous to an artery; these are facts which
are confirmed by simple ocular inspection, as well as by a division of
the vessel, when the blood is seen to be projected by each pulsation of
the heart.

The same thing is also not difficult of demonstration in those animals
that have either no more, or, as it were, no more than a single
ventricle to the heart, such as toads, frogs, serpents, and lizards,
which, although they have lungs in a certain sense, as they have a
voice, (and I have many observations by me on the admirable structure
of the lungs of these animals, and matters appertaining, which,
however, I cannot introduce in this place,) still their anatomy plainly
shows that the blood is transferred in them from the veins to the
arteries in the same manner as in higher animals, viz. by the action
of the heart; the way, in fact, is patent, open, manifest; there is no
difficulty, no room for hesitating about it; for in them the matter
stands precisely as it would in man, were the septum of his heart
perforated or removed, or one ventricle made out of two; and this being
the case, I imagine that no one will doubt as to the way by which the
blood may pass from the veins into the arteries.

But as there are actually more animals which have no lungs than there
are which be furnished with them, and in like manner a greater number
which have only one ventricle than there are which have two, it is
open to us to conclude, judging from the mass or multitude of living
creatures, that for the major part, and generally, there is an open way
by which the blood is transmitted from the veins through the sinuses or
cavities of the heart into the arteries.

I have, however, cogitating with myself, seen further, that the same
thing obtained most obviously in the embryos of those animals that
have lungs; for in the fœtus the four vessels belonging to the heart,
viz. the vena cava, the vena arteriosa or pulmonary artery, the
arteria venalis or pulmonary vein, and the arteria magna or aorta,
are all connected otherwise than in the adult; a fact sufficiently
known to every anatomist. The first contact and union of the vena cava
with the arteria venosa or pulmonary veins, which occurs before the
cava opens properly into the right ventricle of the heart, or gives
off the coronary vein, a little above its escape from the liver, is
by a lateral anastomosis; this is an ample foramen, of an oval form,
communicating between the cava and the arteria venosa, or pulmonary
vein, so that the blood is free to flow in the greatest abundance by
that foramen from the vena cava into the arteria venosa or pulmonary
vein, and left auricle, and from thence into the left ventricle; and
farther, in this foramen ovale, from that part which regards the
arteria venosa, or pulmonary vein, there is a thin tough membrane,
larger than the opening, extended like an operculum or cover; this
membrane in the adult blocking up the foramen, and adhering on all
sides, finally closes it up, and almost obliterates every trace of it.
This membrane, however, is so contrived in the fœtus, that falling
loosely upon itself, it permits a ready access to the lungs and heart,
yielding a passage to the blood which is streaming from the cava, and
hindering the tide at the same time from flowing back into that vein.
All things, in short, permit us to believe that in the embryo the
blood must constantly pass by this foramen from the vena cava into
the arteria venosa, or pulmonary vein, and from thence into the left
auricle of the heart; and having once entered there, it can never

Another union is that by the vena arteriosa, or pulmonary artery,
and is effected when that vessel divides into two branches after its
escape from the right ventricle of the heart. It is as if to the two
trunks already mentioned a third was superadded, a kind of arterial
canal, carried obliquely from the vena arteriosa, or pulmonary artery,
to perforate and terminate in the arteria magna or aorta. In the
embryo, consequently, there are, as it were, two aortas, or two roots
of the arteria magna, springing from the heart. This canalis arteriosus
shrinks gradually after birth, and is at length and finally almost
entirely withered, and removed, like the umbilical vessels.

The canalis arteriosus contains no membrane or valve to direct or
impede the flow of the blood in this or in that direction: for at the
root of the vena arteriosa, or pulmonary artery, of which the canalis
arteriosus is the continuation in the fœtus, there are three sigmoid
or semilunar valves, which open from within outwards, and oppose no
obstacle to the blood flowing in this direction or from the right
ventricle into the pulmonary artery and aorta; but they prevent all
regurgitation from the aorta or pulmonic vessels back upon the right
ventricle; closing with perfect accuracy, they oppose an effectual
obstacle to everything of the kind in the embryo. So that there is also
reason to believe that when the heart contracts, the blood is regularly
propelled by the canal or passage indicated from the right ventricle
into the aorta.

What is commonly said in regard to these two great communications,
to wit, that they exist for the nutrition of the lungs, is both
improbable and inconsistent; seeing that in the adult they are closed
up, abolished, and consolidated, although the lungs, by reason of their
heat and motion, must then be presumed to require a larger supply of
nourishment. The same may be said in regard to the assertion that
the heart in the embryo does not pulsate, that it neither acts nor
moves, so that nature was forced to make these communications for the
nutrition of the lungs. This is plainly false; for simple inspection of
the incubated egg, and of embryos just taken out of the uterus, shows
that the heart moves precisely in them as in adults, and that nature
feels no such necessity. I have myself repeatedly seen these motions,
and Aristotle is likewise witness of their reality. “The pulse,” he
observes, “inheres in the very constitution of the heart, and appears
from the beginning, as is learned both from the dissection of living
animals, and the formation of the chick in the egg.”[27] But we further
observe, that the passages in question are not only pervious up to the
period of birth in man, as well as in other animals, as anatomists
in general have described them, but for several months subsequently,
in some indeed for several years, not to say for the whole course of
life; as, for example, in the goose, snipe, and various birds, and many
of the smaller animals. And this circumstance it was, perhaps, that
imposed upon Botallus, who thought he had discovered a new passage for
the blood from the vena cava into the left ventricle of the heart; and
I own that when I met with the same arrangement in one of the larger
members of the mouse family, in the adult state, I was myself at first
led to something of a like conclusion.

  [27] Lib. de Spiritu, cap. v.

From this it will be understood that in the human embryo, and in the
embryos of animals in which the communications are not closed, the same
thing happens, namely, that the heart by its motion propels the blood
by obvious and open passages from the vena cava into the aorta through
the cavities of both the ventricles; the right one receiving the blood
from the auricle, and propelling it by the vena arteriosa, or pulmonary
artery, and its continuation, named the ductus arteriosus, into the
aorta; the left, in like manner, charged by the contraction of its
auricle, which has received its supply through the foramen ovale from
the vena cava, contracting, and projecting the blood through the root
of the aorta into the trunk of that vessel.

In embryos, consequently, whilst the lungs are yet in a state of
inaction, performing no function, subject to no motion any more than
if they had not been present, nature uses the two ventricles of the
heart as if they formed but one, for the transmission of the blood.
The condition of the embryos of those animals which have lungs, whilst
these organs are yet in abeyance and not employed, is the same as that
of those animals which have no lungs.

So clearly, therefore, does it appear in the case of the fœtus, viz.
that the heart by its action transfers the blood from the vena cava
into the aorta, and that by a route as obvious and open, as if in
the adult the two ventricles were made to communicate by the removal
of their septum. Since, then, we find that in the greater number of
animals, in all, indeed, at a certain period of their existence,
the channels for the transmission of the blood through the heart
are so conspicuous, we have still to inquire wherefore in some
creatures--those, namely, that have warm blood, and that have attained
to the adult age, man among the number--we should not conclude that the
same thing is accomplished through the substance of the lungs, which
in the embryo, and at a time when the function of these organs is in
abeyance, nature effects by the direct passages described, and which,
indeed, she seems compelled to adopt through want of a passage by the
lungs; or wherefore it should be better (for nature always does that
which is best) that she should close up the various open routes which
she had formerly made use of in the embryo and fœtus, and still uses in
all other animals; not only opening up no new apparent channels for the
passage of the blood, therefore, but even entirely shutting up those
which formerly existed.

And now the discussion is brought to this point, that they who inquire
into the ways by which the blood reaches the left ventricle of the
heart and pulmonary veins from the vena cava, will pursue the wisest
course if they seek by dissection to discover the causes why in the
larger and more perfect animals of mature age, nature has rather chosen
to make the blood percolate the parenchyma of the lungs, than as
in other instances chosen a direct and obvious course--for I assume
that no other path or mode of transit can be entertained. It must be
either because the larger and more perfect animals are warmer, and
when adult their heat greater--ignited, as I might say, and requiring
to be damped or mitigated; therefore it may be that the blood is
sent through the lungs, that it may be tempered by the air that is
inspired, and prevented from boiling up, and so becoming extinguished,
or something else of the sort. But to determine these matters, and
explain them satisfactorily, were to enter on a speculation in regard
to the office of the lungs and the ends for which they exist; and
upon such a subject, as well as upon what pertains to eventilation,
to the necessity and use of the air, &c., as also to the variety and
diversity of organs that exist in the bodies of animals in connexion
with these matters, although I have made a vast number of observations,
still, lest I should be held as wandering too wide of my present
purpose, which is the use and motion of the heart, and be charged
with speaking of things beside the question, and rather complicating
and quitting than illustrating it, I shall leave such topics till I
can more conveniently set them forth in a treatise apart. And now,
returning to my immediate subject, I go on with what yet remains for
demonstration, viz. that in the more perfect and warmer adult animals,
and man, the blood passes from the right ventricle of the heart by the
vena arteriosa, or pulmonary artery, into the lungs, and thence by the
arteriæ venosæ, or pulmonary veins, into the left auricle, and thence
into the left ventricle of the heart. And, first, I shall show that
this may be so, and then I shall prove that it is so in fact.



That this is possible, and that there is nothing to prevent it from
being so, appears when we reflect on the way in which water percolating
the earth produces springs and rivulets, or when we speculate on
the means by which the sweat passes through the skin, or the urine
through the parenchyma of the kidneys. It is well known that persons
who use the Spa waters, or those of La Madonna, in the territories of
Padua, or others of an acidulous or vitriolated nature, or who simply
swallow drinks by the gallon, pass all off again within an hour or
two by urine. Such a quantity of liquid must take some short time in
the concoction: it must pass through the liver; (it is allowed by all
that the juices of the food we consume pass twice through this organ
in the course of the day;) it must flow through the veins, through the
parenchyma of the kidneys, and through the ureters into the bladder.

To those, therefore, whom I hear denying that the blood, aye the whole
mass of the blood may pass through the substance of the lungs, even as
the nutritive juices percolate the liver, asserting such a proposition
to be impossible, and by no means to be entertained as credible, I
reply, with the poet, that they are of that race of men who, when they
will, assent full readily, and when they will not, by no manner of
means; who, when their assent is wanted, fear, and when it is not, fear
not to give it.

The parenchyma of the liver is extremely dense, so is that of the
kidney; the lungs, again, are of a much looser texture, and if
compared with the kidneys are absolutely spongy. In the liver there
is no forcing, no impelling power; in the lungs the blood is forced
on by the pulse of the right ventricle, the necessary effect of whose
impulse is the distension of the vessels and pores of the lungs. And
then the lungs, in respiration, are perpetually rising and falling;
motions, the effect of which must needs be to open and shut the pores
and vessels, precisely as in the case of a sponge, and of parts having
a spongy structure, when they are alternately compressed and again are
suffered to expand. The liver, on the contrary, remains at rest, and
is never seen to be dilated and constricted. Lastly, if no one denies
the possibility of the whole of the ingested juices passing through
the liver, in man, oxen, and the larger animals generally, in order
to reach the vena cava, and for this reason, that if nourishment is
to go on, these juices must needs get into the veins, and there is no
other way but the one indicated, why should not the same arguments
be held of avail for the passage of the blood in adults through the
lungs? Why not, with Columbus, that skilful and learned anatomist,
maintain and believe the like, from the capacity and structure of the
pulmonary vessels; from the fact of the pulmonary veins and ventricle
corresponding with them, being always found to contain blood, which
must needs have come from the veins, and by no other passage save
through the lungs? Columbus, and we also, from what precedes, from
dissections, and other arguments, conceive the thing to be clear. But
as there are some who admit nothing unless upon authority, let them
learn that the truth I am contending for can be confirmed from Galen’s
own words, namely, that not only may the blood be transmitted from the
pulmonary artery into the pulmonary veins, then into the left ventricle
of the heart, and from thence into the arteries of the body, but that
this is effected by the ceaseless pulsation of the heart and the motion
of the lungs in breathing.

There are, as every one knows, three sigmoid or semilunar valves
situated at the orifice of the pulmonary artery, which effectually
prevent the blood sent into the vessel from returning into the cavity
of the heart. Now Galen, explaining the uses of these valves, and
the necessity for them, employs the following language:[28] “There
is everywhere a mutual anastomosis and inosculation of the arteries
with the veins, and they severally transmit both blood and spirit,
by certain invisible and undoubtedly very narrow passages. Now if
the mouth of the vena arteriosa, or pulmonary artery, had stood in
like manner continually open, and nature had found no contrivance for
closing it when requisite, and opening it again, it would have been
impossible that the blood could ever have passed by the invisible
and delicate mouths, during the contractions of the thorax, into the
arteries; for all things are not alike readily attracted or repelled;
but that which is light is more readily drawn in, the instrument being
dilated, and forced out again when it is contracted, than that which
is heavy; and in like manner is anything drawn more rapidly along an
ample conduit, and again driven forth, than it is through a narrow
tube. But when the thorax is contracted, the pulmonary veins, which
are in the lungs, being driven inwardly, and powerfully compressed on
every side, immediately force out some of the spirit they contain, and
at the same time assume a certain portion of blood by those subtile
mouths; a thing that could never come to pass were the blood at liberty
to flow back into the heart through the great orifice of the pulmonary
artery. But its return through this great opening being prevented,
when it is compressed on every side, a certain portion of it distils
into the pulmonary veins by the minute orifices mentioned.” And
shortly afterwards, in the very next chapter, he says: “The more the
thorax contracts, the more it strives to force out the blood, the more
exactly do these membranes (viz. the sigmoid valves) close up the mouth
of the vessel, and suffer nothing to regurgitate.” The same fact he
has also alluded to in a preceding part of the tenth chapter: “Were
there no valves, a three-fold inconvenience would result, so that the
blood would then perform this lengthened course in vain; it would flow
inwards during the diastoles of the lungs, and fill all their arteries;
but in the systoles, in the manner of the tide, it would ever and anon,
like the Euripus, flow backwards and forwards by the same way, with a
reciprocating motion, which would nowise suit the blood. This, however,
may seem a matter of little moment; but if it meantime appear that the
function of respiration suffer, then I think it would be looked upon as
no trifle, &c.” And, again, and shortly afterwards: “And then a third
inconvenience, by no means to be thought lightly of, would follow, were
the blood moved backwards during the expirations, had not our Maker
instituted those supplementary membranes [the sigmoid valves].” Whence,
in the eleventh chapter, he concludes: “That they have all a common
use, (to wit, the valves,) and that it is to prevent regurgitation or
backward motion; each, however, having a proper function, the one set
drawing matters from the heart, and preventing their return, the other
drawing matters into the heart, and preventing their escape from it.
For nature never intended to distress the heart with needless labour,
neither to bring aught into the organ which it had been better to have
kept away, nor to take from it again aught which it was requisite
should be brought. Since, then, there are four orifices in all, two in
either ventricle, one of these induces, the other educes.” And again
he says: “Farther, since there is one vessel, consisting of a simple
tunic, implanted in the heart, and another, having a double tunic,
extending from it, (Galen is here speaking of the right side of the
heart, but I extend his observations to the left side also,) a kind of
reservoir had to be provided, to which both belonging, the blood should
be drawn in by the one, and sent out by the other.”

  [28] De Usu partium, lib. vi. cap. 10.

This argument Galen adduces for the transit of the blood by the right
ventricle from the vena cava into the lungs; but we can use it with
still greater propriety, merely changing the terms, for the passage
of the blood from the veins through the heart into the arteries.
From Galen, however, that great man, that father of physicians, it
clearly appears that the blood passes through the lungs from the
pulmonary artery into the minute branches of the pulmonary veins,
urged to this both by the pulses of the heart and by the motions
of the lungs and thorax; that the heart, moreover, is incessantly
receiving and expelling the blood by and from its ventricles, as from
a magazine or cistern, and for this end is furnished with four sets
of valves, two serving for the induction and two for the eduction of
the blood, lest, like the Euripus, it should be incommodiously sent
hither and thither, or flow back into the cavity which it should
have quitted, or quit the part where its presence was required, and
so the heart be oppressed with labour in vain, and the office of the
lungs be interfered with.[29] Finally, our position that the blood is
continually passing from the right to the left ventricle, from the vena
cava into the aorta, through the porous structure of the lungs, plainly
appears from this, that since the blood is incessantly sent from the
right ventricle into the lungs by the pulmonary artery, and in like
manner is incessantly drawn from the lungs into the left ventricle, as
appears from what precedes and the position of the valves, it cannot
do otherwise than pass through continuously. And then, as the blood
is incessantly flowing into the right ventricle of the heart, and is
continually passed out from the left, as appears in like manner, and as
is obvious both to sense and reason, it is impossible that the blood
can do otherwise than pass continually from the vena cava into the

  [29] See the Commentary of the learned Hofmann upon the Sixth Book of
  Galen, “De Usu partium,” a work which I first saw after I had written
  what precedes.

Dissection consequently shows distinctly what takes place [in regard to
the transit of the blood] in the greater number of animals, and indeed
in all, up to the period of their [fœtal] maturity; and that the same
thing occurs in adults is equally certain, both from Galen’s words,
and what has already been said on the subject, only that in the former
the transit is effected by open and obvious passages, in the latter by
the obscure porosities of the lungs and the minute inosculations of
vessels. Whence it appears that, although one ventricle of the heart,
the left to wit, would suffice for the distribution of the blood over
the body, and its eduction from the vena cava, as indeed is done in
those creatures that have no lungs, nature, nevertheless, when she
ordained that the same blood should also percolate the lungs, saw
herself obliged to add another ventricle, the right, the pulse of which
should force the blood from the vena cava through the lungs into the
cavity of the left ventricle. In this way, therefore, it may be said
that the right ventricle is made for the sake of the lungs, and for
the transmission of the blood through them, not for their nutrition;
seeing it were unreasonable to suppose that the lungs required any so
much more copious a supply of nutriment, and that of so much purer and
more spirituous a kind, as coming immediately from the ventricle of the
heart, than either the brain with its peculiarly pure substance, or the
eyes with their lustrous and truly admirable structure, or the flesh of
the heart itself, which is more commodiously nourished by the coronary



Thus far I have spoken of the passage of the blood from the veins
into the arteries, and of the manner in which it is transmitted and
distributed by the action of the heart; points to which some, moved
either by the authority of Galen or Columbus, or the reasonings of
others, will give in their adhesion. But what remains to be said upon
the quantity and source of the blood which thus passes, is of so novel
and unheard-of character, that I not only fear injury to myself from
the envy of a few, but I tremble lest I have mankind at large for my
enemies, so much doth wont and custom, that become as another nature,
and doctrine once sown and that hath struck deep root, and respect
for antiquity influence all men: Still the die is cast, and my trust
is in my love of truth, and the candour that inheres in cultivated
minds. And sooth to say, when I surveyed my mass of evidence, whether
derived from vivisections, and my various reflections on them, or from
the ventricles of the heart and the vessels that enter into and issue
from them, the symmetry and size of these conduits,--for nature doing
nothing in vain, would never have given them so large a relative size
without a purpose,--or from the arrangement and intimate structure
of the valves in particular, and of the other parts of the heart in
general, with many things besides, I frequently and seriously bethought
me, and long revolved in my mind, what might be the quantity of
blood which was transmitted, in how short a time its passage might be
effected, and the like; and not finding it possible that this could be
supplied by the juices of the ingested aliment without the veins on
the one hand becoming drained, and the arteries on the other getting
ruptured through the excessive charge of blood, unless the blood should
somehow find its way from the arteries into the veins, and so return
to the right side of the heart; I began to think whether there might
not be a A MOTION, AS IT WERE, IN A CIRCLE. Now this I afterwards found
to be true; and I finally saw that the blood, forced by the action of
the left ventricle into the arteries, was distributed to the body at
large, and its several parts, in the same manner as it is sent through
the lungs, impelled by the right ventricle into the pulmonary artery,
and that it then passed through the veins and along the vena cava, and
so round to the left ventricle in the manner already indicated. Which
motion we may be allowed to call circular, in the same way as Aristotle
says that the air and the rain emulate the circular motion of the
superior bodies; for the moist earth, warmed by the sun, evaporates;
the vapours drawn upwards are condensed, and descending in the form of
rain, moisten the earth again; and by this arrangement are generations
of living things produced; and in like manner too are tempests and
meteors engendered by the circular motion, and by the approach and
recession of the sun.

And so, in all likelihood, does it come to pass in the body, through
the motion of the blood; the various parts are nourished, cherished,
quickened by the warmer, more perfect, vaporous, spirituous, and, as
I may say, alimentive blood; which, on the contrary, in contact with
these parts becomes cooled, coagulated, and, so to speak, effete;
whence it returns to its sovereign the heart, as if to its source,
or to the inmost home of the body, there to recover its state of
excellence or perfection. Here it resumes its due fluidity and
receives an infusion of natural heat--powerful, fervid, a kind of
treasury of life, and is impregnated with spirits, and it might be said
with balsam; and thence it is again dispersed; and all this depends on
the motion and action of the heart.

The heart, consequently, is the beginning of life; the sun of the
microcosm, even as the sun in his turn might well be designated the
heart of the world; for it is the heart by whose virtue and pulse
the blood is moved, perfected, made apt to nourish, and is preserved
from corruption and coagulation; it is the household divinity which,
discharging its function, nourishes, cherishes, quickens the whole
body, and is indeed the foundation of life, the source of all action.
But of these things we shall speak more opportunely when we come to
speculate upon the final cause of this motion of the heart.

Hence, since the veins are the conduits and vessels that transport the
blood, they are of two kinds, the cava and the aorta; and this not by
reason of there being two sides of the body, as Aristotle has it, but
because of the difference of office; nor yet, as is commonly said, in
consequence of any diversity of structure, for in many animals, as I
have said, the vein does not differ from the artery in the thickness
of its tunics, but solely in virtue of their several destinies and
uses. A vein and an artery, both styled vein by the ancients, and that
not undeservedly, as Galen has remarked, because the one, the artery
to wit, is the vessel which carries the blood from the heart to the
body at large, the other or vein of the present day bringing it back
from the general system to the heart; the former is the conduit from,
the latter the channel to, the heart; the latter contains the cruder,
effete blood, rendered unfit for nutrition; the former transmits the
digested, perfect, peculiarly nutritive fluid.



But lest any one should say that we give them words only, and make
mere specious assertions without any foundation, and desire to
innovate without sufficient cause, three points present themselves for
confirmation, which being stated, I conceive that the truth I contend
for will follow necessarily, and appear as a thing obvious to all.
First,--the blood is incessantly transmitted by the action of the
heart from the vena cava to the arteries in such quantity, that it
cannot be supplied from the ingesta, and in such wise that the whole
mass must very quickly pass through the organ; Second,--the blood
under the influence of the arterial pulse enters and is impelled in
a continuous, equable, and incessant stream through every part and
member of the body, in much larger quantity than were sufficient for
nutrition, or than the whole mass of fluids could supply; Third,--the
veins in like manner return this blood incessantly to the heart from
all parts and members of the body. These points proved, I conceive it
will be manifest that the blood circulates, revolves, propelled and
then returning, from the heart to the extremities, from the extremities
to the heart, and thus that it performs a kind of circular motion.

Let us assume either arbitrarily or from experiment, the quantity of
blood which the left ventricle of the heart will contain when distended
to be, say two ounces, three ounces, one ounce and a half--in the dead
body I have found it to hold upwards of two ounces. Let us assume
further, how much less the heart will hold in the contracted than in
the dilated state; and how much blood it will project into the aorta
upon each contraction;--and all the world allows that with the systole
something is always projected, a necessary consequence demonstrated in
the third chapter, and obvious from the structure of the valves; and
let us suppose as approaching the truth that the fourth, or fifth, or
sixth, or even but the eighth part of its charge is thrown into the
artery at each contraction; this would give either half an ounce, or
three drachms, or one drachm of blood as propelled by the heart at each
pulse into the aorta; which quantity, by reason of the valves at the
root of the vessel, can by no means return into the ventricle. Now,
in the course of half an hour, the heart will have made more than one
thousand beats, in some as many as two, three, and even four thousand.
Multiplying the number of drachms propelled by the number of pulses, we
shall have either one thousand half-ounces, or one thousand times three
drachms, or a like proportional quantity of blood, according to the
amount which we assume as propelled with each stroke of the heart, sent
from this organ into the artery; a larger quantity in every case than
is contained in the whole body! In the same way, in the sheep or dog,
say that but a single scruple of blood passes with each stroke of the
heart, in one half-hour we should have one thousand scruples, or about
three pounds and a half of blood injected into the aorta; but the body
of neither animal contains above four pounds of blood, a fact which I
have myself ascertained in the case of the sheep.

Upon this supposition, therefore, assumed merely as a ground for
reasoning, we see the whole mass of blood passing through the heart,
from the veins to the arteries, and in like manner through the lungs.

But let it be said that this does not take place in half an hour, but
in an hour, or even in a day; any way it is still manifest that more
blood passes through the heart in consequence of its action, than
can either be supplied by the whole of the ingesta, or than can be
contained in the veins at the same moment.

Nor can it be allowed that the heart in contracting sometimes propels
and sometimes does not propel, or at most propels but very little,
a mere nothing, or an imaginary something: all this, indeed, has
already been refuted; and is, besides, contrary both to sense and
reason. For if it be a necessary effect of the dilatation of the heart
that its ventricles become filled with blood, it is equally so that,
contracting, these cavities should expel their contents; and this not
in any trifling measure, seeing that neither are the conduits small,
nor the contractions few in number, but frequent, and always in some
certain proportion, whether it be a third, or a sixth, or an eighth,
to the total capacity of the ventricles, so that a like proportion of
blood must be expelled, and a like proportion received with each stroke
of the heart, the capacity of the ventricle contracted always bearing
a certain relation to the capacity of the ventricle when dilated. And
since in dilating, the ventricles cannot be supposed to get filled with
nothing, or with an imaginary something; so in contracting they never
expel nothing or aught imaginary, but always a certain something, viz.
blood, in proportion to the amount of the contraction. Whence it is to
be inferred, that if at one stroke the heart in man, the ox, or the
sheep, ejects but a single drachm of blood, and there are one thousand
strokes in half an hour, in this interval there will have been ten
pounds five ounces expelled: were there with each stroke two drachms
expelled, the quantity would of course amount to twenty pounds and ten
ounces; were there half an ounce, the quantity would come to forty-one
pounds and eight ounces; and were there one ounce, it would be as much
as eighty-three pounds and four ounces; the whole of which, in the
course of one half-hour, would have been transfused from the veins to
the arteries. The actual quantity of blood expelled at each stroke of
the heart, and the circumstances under which it is either greater or
less than ordinary, I leave for particular determination afterwards,
from numerous observations which I have made on the subject.

Meantime this much I know, and would here proclaim to all, that the
blood is transfused at one time in larger, at another in smaller
quantity; and that the circuit of the blood is accomplished now more
rapidly, now more slowly, according to the temperament, age, &c., of
the individual, to external and internal circumstances, to naturals and
non-naturals,--sleep, rest, food, exercise, affections of the mind, and
the like. But indeed, supposing even the smallest quantity of blood to
be passed through the heart and the lungs with each pulsation, a vastly
greater amount would still be thrown into the arteries and whole body,
than could by any possibility be supplied by the food consumed; in
short it could be furnished in no other way than by making a circuit
and returning.

This truth, indeed, presents itself obviously before us when we
consider what happens in the dissection of living animals; the great
artery need not be divided, but a very small branch only, (as Galen
even proves in regard to man,) to have the whole of the blood in the
body, as well that of the veins as of the arteries, drained away in the
course of no long time--some half-hour or less. Butchers are well aware
of the fact and can bear witness to it; for, cutting the throat of an
ox and so dividing the vessels of the neck, in less than a quarter
of an hour they have all the vessels bloodless--the whole mass of
blood has escaped. The same thing also occasionally occurs with great
rapidity in performing amputations and removing tumours in the human

Nor would this argument lose any of its force, did any one say that in
killing animals in the shambles, and performing amputations, the blood
escaped in equal, if not perchance in larger quantity by the veins than
by the arteries. The contrary of this statement, indeed, is certainly
the truth; the veins, in fact, collapsing, and being without any
propelling power, and further, because of the impediment of the valves,
as I shall show immediately, pour out but very little blood; whilst the
arteries spout it forth with force abundantly, impetuously, and as if
it were propelled by a syringe. And then the experiment is easily tried
of leaving the vein untouched, and only dividing the artery in the
neck of a sheep or dog, when it will be seen with what force, in what
abundance, and how quickly, the whole blood in the body, of the veins
as well as of the arteries, is emptied. But the arteries receive blood
from the veins in no other way than by transmission through the heart,
as we have already seen; so that if the aorta be tied at the base of
the heart, and the carotid or any other artery be opened, no one will
now be surprised to find it empty, and the veins only replete with

And now the cause is manifest, wherefore in our dissections we usually
find so large a quantity of blood in the veins, so little in the
arteries; wherefore there is much in the right ventricle, little in the
left; circumstances which probably led the ancients to believe that
the arteries (as their name implies) contained nothing but spirits
during the life of an animal. The true cause of the difference is this
perhaps: that as there is no passage to the arteries, save through the
lungs and heart, when an animal has ceased to breathe and the lungs to
move, the blood in the pulmonary artery is prevented from passing into
the pulmonary veins, and from thence into the left ventricle of the
heart; just as we have already seen the same transit prevented in the
embryo, by the want of movement in the lungs and the alternate opening
and shutting of their minute orifices and invisible pores. But the
heart not ceasing to act at the same precise moment as the lungs, but
surviving them and continuing to pulsate for a time, the left ventricle
and arteries go on distributing their blood to the body at large and
sending it into the veins; receiving none from the lungs, however,
they are soon exhausted and left, as it were, empty. But even this
fact confirms our views, in no trifling manner, seeing that it can be
ascribed to no other than the cause we have just assumed.

Moreover it appears from this that the more frequently or forcibly
the arteries pulsate, the more speedily will the body be exhausted in
an hemorrhagy. Hence, also, it happens, that in fainting fits and in
states of alarm, when the heart beats more languidly and with less
force, hemorrhages are diminished or arrested.

Still further, it is from this that after death, when the heart has
ceased to beat, it is impossible by dividing either the jugular or
femoral veins and arteries, by any effort to force out more than one
half of the whole mass of the blood. Neither could the butcher, did he
neglect to cut the throat of the ox which he has knocked on the head
and stunned, until the heart had ceased beating, ever bleed the carcass

Finally, we are now in a condition to suspect wherefore it is that no
one has yet said anything to the purpose upon the anastomosis of the
veins and arteries, either as to where or how it is effected, or for
what purpose. I now enter upon the investigation of the subject.



So far our first position is confirmed, whether the thing be referred
to calculation or to experiment and dissection, viz. that the blood
is incessantly infused into the arteries in larger quantities than it
can be supplied by the food; so that the whole passing over in a short
space of time, it is matter of necessity that the blood perform a
circuit, that it return to whence it set out.

But if any one shall here object that a large quantity may pass through
and yet no necessity be found for a circulation, that all may come from
the meat and drink consumed, and quote as an illustration the abundant
supply of milk in the mammæ--for a cow will give three, four, and even
seven gallons and more in a day, and a woman two or three pints whilst
nursing a child or twins, which must manifestly be derived from the
food consumed; it may be answered, that the heart by computation does
as much and more in the course of an hour or two.

And if not yet convinced, he shall still insist, that when an artery
is divided a preternatural route is, as it were, opened, and that so
the blood escapes in torrents, but that the same thing does not happen
in the healthy and uninjured body when no outlet is made; and that
in arteries filled, or in their natural state, so large a quantity of
blood cannot pass in so short a space of time as to make any return
necessary;--to all this it may be answered, that from the calculation
already made, and the reasons assigned, it appears, that by so much as
the heart in its dilated state contains in addition to its contents in
the state of constriction, so much in a general way must it emit upon
each pulsation, and in such quantity must the blood pass, the body
being healthy and naturally constituted.

But in serpents, and several fishes, by tying the veins some way below
the heart, you will perceive a space between the ligature and the heart
speedily to become empty; so that, unless you would deny the evidence
of your senses, you must needs admit the return of the blood to the
heart. The same thing will also plainly appear when we come to discuss
our second position.

Let us here conclude with a single example, confirming all that has
been said, and from which every one may obtain conviction through the
testimony of his own eyes.

If a live snake be laid open, the heart will be seen pulsating quietly,
distinctly, for more than an hour, moving like a worm, contracting
in its longitudinal dimensions, (for it is of an oblong shape,) and
propelling its contents; becoming of a paler colour in the systole,
of a deeper tint in the diastole; and almost all things else by which
I have already said that the truth I contend for is established, only
that here everything takes place more slowly, and is more distinct.
This point in particular may be observed more clearly than the noon-day
sun: the vena cava enters the heart at its lower part, the artery quits
it at the superior part; the vein being now seized either with forceps
or between the finger and thumb, and the course of the blood for some
space below the heart interrupted, you will perceive the part that
intervenes between the fingers and the heart almost immediately to
become empty, the blood being exhausted by the action of the heart;
at the same time the heart will become of a much paler colour, even in
its state of dilatation, than it was before; it is also smaller than at
first, from wanting blood; and then it begins to beat more slowly, so
that it seems at length as if it were about to die. But the impediment
to the flow of blood being removed, instantly the colour and the size
of the heart are restored.

If, on the contrary, the artery instead of the vein be compressed or
tied, you will observe the part between the obstacle and the heart, and
the heart itself, to become inordinately distended, to assume a deep
purple or even livid colour, and at length to be so much oppressed with
blood that you will believe it about to be choked; but the obstacle
removed, all things immediately return to their pristine state--the
heart to its colour, size, stroke, &c.

Here then we have evidence of two kinds of death: extinction from
deficiency, and suffocation from excess. Examples of both have now
been set before you, and you have had opportunity of viewing the truth
contended for with your own eyes in the heart.



That this may the more clearly appear to every one, I have here to
cite certain experiments, from which it seems obvious that the blood
enters a limb by the arteries, and returns from it by the veins; that
the arteries are the vessels carrying the blood from the heart, and the
veins the returning channels of the blood to the heart; that in the
limbs and extreme parts of the body the blood passes either immediately
by anastomosis from the arteries into the veins, or mediately by
the pores of the flesh, or in both ways, as has already been said
in speaking of the passage of the blood through the lungs; whence
it appears manifest that in the circuit the blood moves from thence
hither, and from hence thither; from the centre to the extremities, to
wit; and from the extreme parts back again to the centre. Finally, upon
grounds of calculation, with the same elements as before, it will be
obvious that the quantity can neither be accounted for by the ingesta,
nor yet be held necessary to nutrition.

The same thing will also appear in regard to ligatures, and wherefore
they are said to _draw_; though this is neither from the heat, nor
the pain, nor the vacuum they occasion, nor indeed from any other
cause yet thought of; it will also explain the uses and advantages to
be derived from ligatures in medicine, the principle upon which they
either suppress or occasion hemorrhage; how they induce sloughing and
more extensive mortification in extremities; and how they act in the
castration of animals and the removal of warts and fleshy tumours. But
it has come to pass, from no one having duly weighed and understood the
causes and rationale of these various effects, that though almost all,
upon the faith of the old writers, recommend ligatures in the treatment
of disease, yet very few comprehend their proper employment, or derive
any real assistance from them in effecting cures.

Ligatures are either very tight or of middling tightness. A ligature
I designate as tight or perfect when it is drawn so close about an
extremity that no vessel can be felt pulsating beyond it. Such a
ligature we use in amputations to control the flow of blood; and such
also are employed in the castration of animals and the removal of
tumours. In the latter instances, all afflux of nutriment and heat
being prevented by the ligature, we see the testes and large fleshy
tumours dwindle, and die, and finally fall off.

Ligatures of middling tightness I regard as those which compress a
limb firmly all around, but short of pain, and in such a way as still
suffers a certain degree of pulsation to be felt in the artery beyond
them. Such a ligature is in use in blood-letting, an operation in which
the fillet applied above the elbow is not drawn so tight but that the
arteries at the wrist may still be felt beating under the finger.

Now let any one make an experiment upon the arm of a man, either
using such a fillet as is employed in blood-letting, or grasping the
limb tightly with his hand, the best subject for it being one who is
lean, and who has large veins, and the best time after exercise, when
the body is warm, the pulse is full, and the blood carried in larger
quantities to the extremities, for all then is more conspicuous; under
such circumstances let a ligature be thrown about the extremity, and
drawn as tightly as can be borne, it will first be perceived that
beyond the ligature, neither in the wrist, nor anywhere else, do the
arteries pulsate, at the same time that immediately above the ligature
the artery begins to rise higher at each diastole, to throb more
violently, and to swell in its vicinity with a kind of tide, as if
it strove to break through and overcome the obstacle to its current;
the artery, here, in short, appears as if it were preternaturally
full. The hand under such circumstances retains its natural colour
and appearance; in the course of time it begins to fall somewhat in
temperature, indeed, but nothing is _drawn_ into it.

After the bandage has been kept on for some short time in this way, let
it be slackened a little, brought to that state or term of middling
tightness which is used in bleeding, and it will be seen that the whole
hand and arm will instantly become deeply suffused and distended, and
the veins show themselves tumid and knotted; after ten or fifteen
pulses of the artery, the hand will be perceived excessively distended,
injected, gorged with blood, _drawn_, as it is said, by this middling
ligature, without pain, or heat, or any horror of a vacuum, or any
other cause yet indicated.

If the finger be applied over the artery as it is pulsating by the edge
of the fillet, at the moment of slackening it, the blood will be felt
to glide through, as it were, underneath the finger; and he, too, upon
whose arm the experiment is made, when the ligature is slackened, is
distinctly conscious of a sensation of warmth, and of something, viz.
a stream of blood, suddenly making its way along the course of the
vessels and diffusing itself through the hand, which at the same time
begins to feel hot, and becomes distended.

As we had noted, in connexion with the tight ligature, that the artery
above the bandage was distended and pulsated, not below it, so, in the
case of the moderately tight bandage, on the contrary, do we find that
the veins below, never above, the fillet, swell, and become dilated,
whilst the arteries shrink; and such is the degree of distension of
the veins here, that it is only very strong pressure that will force
the blood beyond the fillet, and cause any of the veins in the upper
part of the arm to rise.

From these facts it is easy for every careful observer to learn that
the blood enters an extremity by the arteries; for when they are
effectually compressed nothing is _drawn_ to the member; the hand
preserves its colour; nothing flows into it, neither is it distended;
but when the pressure is diminished, as it is with the bleeding fillet,
it is manifest that the blood is instantly thrown in with force, for
then the hand begins to swell; which is as much as to say, that when
the arteries pulsate the blood is flowing through them, as it is
when the moderately tight ligature is applied; but where they do not
pulsate, as when a tight ligature is used, they cease from transmitting
anything; they are only distended above the part where the ligature is
applied. The veins again being compressed, nothing can flow through
them; the certain indication of which is, that below the ligature they
are much more tumid than above it, and than they usually appear when
there is no bandage upon the arm.

It therefore plainly appears that the ligature prevents the return
of the blood through the veins to the parts above it, and maintains
those beneath it in a state of permanent distension. But the arteries,
in spite of its pressure, and under the force and impulse of the
heart, send on the blood from the internal parts of the body to the
parts beyond the bandage. And herein consists the difference between
the tight and the medium bandage, that the former not only prevents
the passage of the blood in the veins, but in the arteries also; the
latter, however, whilst it does not prevent the pulsific force from
extending beyond it, and so propelling the blood to the extremities of
the body, compresses the veins, and greatly or altogether impedes the
return of the blood through them.

Seeing, therefore, that the moderately tight ligature renders the veins
turgid, and the whole hand full of blood, I ask, whence is this? Does
the blood accumulate below the ligature coming through the veins, or
through the arteries, or passing by certain secret pores? Through the
veins it cannot come; still less can it come by any system of invisible
pores; it must needs arrive by the arteries, then, in conformity with
all that has been already said. That it cannot flow in by the veins
appears plainly enough from the fact that the blood cannot be forced
towards the heart unless the ligature be removed; when on a sudden all
the veins collapse, and disgorge themselves of their contents into the
superior parts, the hand at the same time resuming its natural pale
colour--the tumefaction and the stagnating blood have disappeared.

Moreover, he whose arm or wrist has thus been bound for some little
time with the medium bandage, so that it has not only got swollen and
livid but cold, when the fillet is undone is aware of something cold
making its way upwards along with the returning blood, and reaching the
elbow or the axilla. And I have myself been inclined to think that this
cold blood rising upward to the heart was the cause of the fainting
that often occurs after blood-letting: fainting frequently supervenes
even in robust subjects, and mostly at the moment of undoing the
fillet, as the vulgar say, from the turning of the blood.

Farther, when we see the veins below the ligature instantly swell up
and become gorged, when from extreme tightness it is somewhat relaxed,
the arteries meantime continuing unaffected, this is an obvious
indication that the blood passes from the arteries into the veins,
and not from the veins into the arteries, and that there is either an
anastomosis of the two orders of vessels, or pores in the flesh and
solid parts generally that are permeable to the blood. It is farther
an indication that the veins have frequent communications with one
another, because they all become turgid together, whilst under the
medium ligature applied above the elbow; and if any single small vein
be pricked with a lancet, they all speedily shrink, and disburthening
themselves into this they subside almost simultaneously.

These considerations will enable any one to understand the nature of
the attraction that is exerted by ligatures, and perchance of fluxes
generally; how, for example, the veins when compressed by a bandage
of medium tightness applied above the elbow, the blood cannot escape,
whilst it still continues to be driven in, to wit, by the forcing
power of the heart, by which the parts are of necessity filled, gorged
with blood. And how should it be otherwise? Heat and pain and the _vis
vacui_ draw, indeed; but in such wise only that parts are filled, not
preternaturally distended or gorged, not so suddenly and violently
overwhelmed with the charge of blood forced in upon them, that the
flesh is lacerated and the vessels ruptured. Nothing of the kind as an
effect of heat, or pain, or the vacuum force, is either credible or

Besides, the ligature is competent to occasion the afflux in question
without either pain, or heat, or _vis vacui_. Were pain in any way the
cause, how should it happen that, with the arm bound above the elbow,
the hand and fingers should swell below the bandage, and their veins
become distended? The pressure of the bandage certainly prevents the
blood from getting there by the veins. And then, wherefore is there
neither swelling nor repletion of the veins, nor any sign or symptom of
attraction or afflux, above the ligature? But this is the obvious cause
of the preternatural attraction and swelling below the bandage, and in
the hand and fingers, that the blood is entering abundantly, and with
force, but cannot pass out again.

Now, is not this the cause of all tumefaction, as indeed Avicenna has
it, and of all oppressive redundancy in parts, that the access to them
is open, but the egress from them is closed? Whence it comes that they
are gorged and tumefied. And may not the same thing happen in local
inflammations, where, so long as the swelling is on the increase, and
has not reached its extreme term, a full pulse is felt in the part,
especially when the disease is of the more acute kind, and the swelling
usually takes place most rapidly. But these are matters for after
discussion. Or does this, which occurred in my own case, happen from
the same cause? Thrown from a carriage upon one occasion, I struck my
forehead a blow upon the place where a twig of the artery advances from
the temple, and immediately, within the time in which twenty beats
could have been made, I felt a tumour the size of an egg developed,
without either heat or any great pain: the near vicinity of the artery
had caused the blood to be effused into the bruised part with unusual
force and quickness.

And now, too, we understand wherefore in phlebotomy we apply our fillet
above the part that is punctured, not below it; did the flow come from
above, not from below, the bandage in this case would not only be of
no service, but would prove a positive hinderance; it would have to be
applied below the orifice, in order to have the flow more free, did
the blood descend by the veins from superior to inferior parts; but as
it is elsewhere forced through the extreme arteries into the extreme
veins, and the return in these last is opposed by the ligature, so do
they fill and swell, and being thus filled and distended, they are made
capable of projecting their charge with force, and to a distance, when
any one of them is suddenly punctured; but the fillet being slackened,
and the returning channels thus left open, the blood forthwith no
longer escapes, save by drops; and, as all the world knows, if in
performing phlebotomy the bandage be either slackened too much or the
limb be bound too tightly, the blood escapes without force, because in
the one case the returning channels are not adequately obstructed; the
other the channels of influx, the arteries, are impeded.



If these things be so, another point which I have already referred to,
viz. the continual passage of the blood through the heart, will also be
confirmed. We have seen, that the blood passes from the arteries into
the veins, not from the veins into the arteries; we have seen, farther,
that almost the whole of the blood may be withdrawn from a puncture
made in one of the cutaneous veins of the arm if a bandage properly
applied be used; we have seen, still farther, that the blood flows
so freely and rapidly that not only is the whole quantity which was
contained in the arm beyond the ligature, and before the puncture was
made, discharged, but the whole which is contained in the body, both
that of the arteries and that of the veins.

Whence we must admit, first, that the blood is sent along with an
impulse, and that it is urged with force below the fillet; for it
escapes with force, which force it receives from the pulse and power
of the heart; for the force and motion of the blood are derived from
the heart alone. Second, that the afflux proceeds from the heart, and
through the heart by a course from the great veins [into the aorta];
for it gets into the parts below the ligature through the arteries,
not through the veins; and the arteries nowhere receive blood from the
veins, nowhere receive blood save and except from the left ventricle
of the heart. Nor could so large a quantity of blood be drawn from one
vein (a ligature having been duly applied), nor with such impetuosity,
such readiness, such celerity, unless through the medium of the
impelling power of the heart.

But if all things be as they are now represented, we shall feel
ourselves at liberty to calculate the quantity of the blood, and
to reason on its circular motion. Should any one, for instance, in
performing phlebotomy, suffer the blood to flow in the manner it
usually does, with force and freely, for some half-hour or so, no
question but that the greatest part of the blood being abstracted,
faintings and syncopes would ensue, and that not only would the
arteries but the great veins also be nearly emptied of their contents.
It is only consonant with reason to conclude that in the course of
the half-hour hinted at, so much as has escaped has also passed from
the great veins through the heart into the aorta. And further, if we
calculate how many ounces flow through one arm, or how many pass in
twenty or thirty pulsations under the medium ligature, we shall have
some grounds for estimating how much passes through the other arm
in the same space of time; how much through both lower extremities,
how much through the neck on either side, and through all the other
arteries and veins of the body, all of which have been supplied with
fresh blood, and as this blood must have passed through the lungs and
ventricles of the heart, and must have come from the great veins,--we
shall perceive that a circulation is absolutely necessary, seeing
that the quantities hinted at cannot be supplied immediately from
the ingesta, and are vastly more than can be requisite for the mere
nutrition of the parts.

It is still further to be observed, that the truths contended for
are sometimes confirmed in another way; for having tied up the arm
properly, and made the puncture duly, still, if from alarm or any other
causes, a state of faintness supervenes, in which the heart always
pulsates more languidly, the blood does not flow freely, but distils by
drops only. The reason is, that with the somewhat greater than usual
resistance offered to the transit of the blood by the bandage, coupled
with the weaker action of the heart, and its diminished impelling
power, the stream cannot make its way under the fillet; and farther,
owing to the weak and languishing state of the heart, the blood is not
transferred in such quantity as wont from the veins to the arteries
through the sinuses of that organ. So also, and for the same reasons,
are the menstrual fluxes of women, and indeed hemorrhagies of every
kind, controlled. And now, a contrary state of things occurring,
the patient getting rid of his fear and recovering his courage, the
pulsific power is increased, the arteries begin again to beat with
greater force, and to drive the blood even into the part that is bound;
so that the blood now springs from the puncture in the vein, and flows
in a continuous stream.



Thus far have we spoken of the quantity of blood passing through the
heart and the lungs in the centre of the body, and in like manner from
the arteries into the veins in the peripheral parts and the body at
large. We have yet to explain, however, in what manner the blood finds
its way back to the heart from the extremities by the veins, and how
and in what way these are the only vessels that convey the blood from
the external to the central parts; which done, I conceive that the
three fundamental propositions laid down for the circulation of the
blood will be so plain, so well established, so obviously true, that
they may claim general credence. Now the remaining position will be
made sufficiently clear from the valves which are found in the cavities
of the veins themselves, from the uses of these, and from experiments
cognizable by the senses.

The celebrated Hieronymus Fabricius of Aquapendente, a most skilful
anatomist, and venerable old man, or, as the learned Riolan will have
it, Jacobus Silvius, first gave representations of the valves in the
veins, which consist of raised or loose portions of the inner membranes
of these vessels, of extreme delicacy, and a sigmoid or semilunar
shape. They are situated at different distances from one another, and
diversely in different individuals; they are connate at the sides of
the veins; they are directed upwards or towards the trunks of the
veins; the two--for there are for the most part two together--regard
each other, mutually touch, and are so ready to come into contact by
their edges, that if anything attempt to pass from the trunks into the
branches of the veins, or from the greater vessels into the less, they
completely prevent it; they are farther so arranged, that the horns of
those that succeed are opposite the middle of the convexity of those
that precede, and so on alternately.

The discoverer of these valves did not rightly understand their use,
nor have succeeding anatomists added anything to our knowledge: for
their office is by no means explained when we are told that it is to
hinder the blood, by its weight, from all flowing into inferior parts;
for the edges of the valves in the jugular veins hang downwards, and
are so contrived that they prevent the blood from rising upwards; the
valves, in a word, do not invariably look upwards, but always towards
the trunks of the veins, invariably towards the seat of the heart. I,
and indeed others, have sometimes found valves in the emulgent veins,
and in those of the mesentery, the edges of which were directed towards
the vena cava and vena portæ. Let it be added that there are no valves
in the arteries [save at their roots], and that dogs, oxen, &c., have
invariably valves at the divisions of their crural veins, in the veins
that meet towards the top of the os sacrum, and in those branches which
come from the haunches, in which no such effect of gravity from the
erect position was to be apprehended. Neither are there valves in the
jugular veins for the purpose of guarding against apoplexy, as some
have said; because in sleep the head is more apt to be influenced by
the contents of the carotid arteries. Neither are the valves present,
in order that the blood may be retained in the divarications or smaller
trunks and minuter branches, and not be suffered to flow entirely
into the more open and capacious channels; for they occur where there
are no divarications; although it must be owned that they are most
frequent at the points where branches join. Neither do they exist for
the purpose of rendering the current of blood more slow from the centre
of the body; for it seems likely that the blood would be disposed to
flow with sufficient slowness of its own accord, as it would have to
pass from larger into continually smaller vessels, being separated
from the mass and fountain head, and attaining from warmer into colder

But the valves are solely made and instituted lest the blood should
pass from the greater into the lesser veins, and either rupture them
or cause them to become varicose; lest, instead of advancing from the
extreme to the central parts of the body, the blood should rather
proceed along the veins from the centre to the extremities; but the
delicate valves, while they readily open in the right direction,
entirely prevent all such contrary motion, being so situated and
arranged, that if anything escapes, or is less perfectly obstructed
by the cornua of the one above, the fluid passing, as it were, by the
chinks between the cornua, it is immediately received on the convexity
of the one beneath, which is placed transversely with reference to the
former, and so is effectually hindered from getting any farther.

And this I have frequently experienced in my dissections of the veins:
if I attempted to pass a probe from the trunk of the veins into one
of the smaller branches, whatever care I took I found it impossible
to introduce it far any way, by reason of the valves; whilst, on the
contrary, it was most easy to push it along in the opposite direction,
from without inwards, or from the branches towards the trunks and
roots. In many places two valves are so placed and fitted, that when
raised they come exactly together in the middle of the vein, and
are there united by the contact of their margins; and so accurate
is the adaptation, that neither by the eye nor by any other means
of examination can the slightest chink along the line of contact
be perceived. But if the probe be now introduced from the extreme
towards the more central parts, the valves, like the floodgates of
a river, give way, and are most readily pushed aside. The effect of
this arrangement plainly is to prevent all motion of the blood from
the heart and vena cava, whether it be upwards towards the head, or
downwards towards the feet, or to either side towards the arms, not a
drop can pass; all motion of the blood, beginning in the larger and
tending towards the smaller veins, is opposed and resisted by them;
whilst the motion that proceeds from the lesser to end in the larger
branches is favoured, or, at all events, a free and open passage is
left for it.

But that this truth may be made the more apparent, let an arm be
tied up above the elbow as if for phlebotomy (A, A, fig. 1). At
intervals in the course of the veins, especially in labouring people
and those whose veins are large, certain knots or elevations (B, C,
D, E, F) will be perceived, and this not only at the places where a
branch is received (E, F), but also where none enters (C, D): these
knots or risings are all formed by valves, which thus show themselves
externally. And now if you press the blood from the space above one
of the valves, from H to O, (fig. 2,) and keep the point of a
finger upon the vein inferiorly, you will see no influx of blood from
above; the portion of the vein between the point of the finger and the
valve O will be obliterated; yet will the vessel continue sufficiently
distended above that valve (O, G). The blood being thus pressed out,
and the vein emptied, if you now apply a finger of the other hand upon
the distended part of the vein above the valve O, (fig. 3,) and
press downwards, you will find that you cannot force the blood through
or beyond the valve; but the greater effort you use, you will only see
the portion of vein that is between the finger and the valve become
more distended, that portion of the vein which is below the valve
remaining all the while empty (H, O, fig. 3).

It would therefore appear that the function of the valves in the veins
is the same as that of the three sigmoid valves which we find at the
commencement of the aorta and pulmonary artery, viz., to prevent all
reflux of the blood that is passing over them.

Farther, the arm being bound as before, and the veins looking full
and distended, if you press at one part in the course of a vein with
the point of a finger (L, fig. 4), and then with another finger
streak the blood upwards beyond the next valve (N), you will perceive
that this portion of the vein continues empty (L N), and that the
blood cannot retrograde, precisely as we have already seen the case
to be in fig. 2; but the finger first applied (H, fig. 2,
L, fig. 4), being removed, immediately the vein is filled from
below, and the arm becomes as it appears at D C, fig. 1. That the
blood in the veins therefore proceeds from inferior or more remote to
superior parts, and towards the heart, moving in these vessels in this
and not in the contrary direction, appears most obviously. And although
in some places the valves, by not acting with such perfect accuracy,
or where there is but a single valve, do not seem totally to prevent
the passage of the blood from the centre, still the greater number
of them plainly do so; and then, where things appear contrived more
negligently, this is compensated either by the more frequent occurrence
or more perfect action of the succeeding valves or in some other way:
the veins, in short, as they are the free and open conduits of the
blood returning _to_ the heart, so are they effectually prevented from
serving as its channels of distribution _from_ the heart.

[Illustration: Fig. 4.]

[Illustration: Fig. 3.]

[Illustration: Fig. 2.]

[Illustration: Fig. 1.]

But this other circumstance has to be noted: The arm being bound, and
the veins made turgid, and the valves prominent, as before, apply the
thumb or finger over a vein in the situation of one of the valves in
such a way as to compress it, and prevent any blood from passing
upwards from the hand; then, with a finger of the other hand, streak
the blood in the vein upwards till it has passed the next valve above,
(N, fig. 4,) the vessel now remains empty; but the finger at L
being removed for an instant, the vein is immediately filled from
below; apply the finger again, and having in the same manner streaked
the blood upwards, again remove the finger below, and again the vessel
becomes distended as before; and this repeat, say a thousand times, in
a short space of time. And now compute the quantity of blood which you
have thus pressed up beyond the valve, and then multiplying the assumed
quantity by one thousand, you will find that so much blood has passed
through a certain portion of the vessel; and I do now believe that you
will find yourself convinced of the circulation of the blood, and of
its rapid motion. But if in this experiment you say that a violence is
done to nature, I do not doubt but that, if you proceed in the same
way, only taking as great a length of vein as possible, and merely
remark with what rapidity the blood flows upwards, and fills the vessel
from below, you will come to the same conclusion.



And now I may be allowed to give in brief my view of the circulation of
the blood, and to propose it for general adoption.

Since all things, both argument and ocular demonstration, show that the
blood passes through the lungs and heart by the action of the [auricles
and] ventricles, and is sent for distribution to all parts of the body,
where it makes its way into the veins and pores of the flesh, and then
flows by the veins from the circumference on every side to the centre,
from the lesser to the greater veins, and is by them finally discharged
into the vena cava and right auricle of the heart, and this in such a
quantity or in such a flux and reflux thither by the arteries, hither
by the veins, as cannot possibly be supplied by the ingesta, and is
much greater than can be required for mere purposes of nutrition; it is
absolutely necessary to conclude that the blood in the animal body is
impelled in a circle, and is in a state of ceaseless motion; that this
is the act or function which the heart performs by means of its pulse;
and that it is the sole and only end of the motion and contraction of
the heart.



It will not be foreign to the subject if I here show further, from
certain familiar reasonings, that the circulation is matter both
of convenience and necessity. In the first place, since death is a
corruption which takes place through deficiency of heat,[30] and since
all living things are warm, all dying things cold, there must be a
particular seat and fountain, a kind of home and hearth, where the
cherisher of nature, the original of the native fire, is stored and
preserved; whence heat and life are dispensed to all parts as from
a fountain head; whence sustenance may be derived; and upon which
concoction and nutrition, and all vegetative energy may depend. Now,
that the heart is this place, that the heart is the principle of life,
and that all passes in the manner just mentioned, I trust no one will

  [30] Aristoteles De Respiratione, lib. ii et iii: De Part. Animal. et

The blood, therefore, required to have motion, and indeed such a motion
that it should return again to the heart; for sent to the external
parts of the body far from its fountain, as Aristotle says, and without
motion, it would become congealed. For we see motion generating and
keeping up heat and spirits under all circumstances, and rest allowing
them to escape and be dissipated. The blood, therefore, become thick or
congealed by the cold of the extreme and outward parts, and robbed of
its spirits, just as it is in the dead, it was imperative that from its
fount and origin, it should again receive heat and spirits, and all
else requisite to its preservation--that, by returning, it should be
renovated and restored.

We frequently see how the extremities are chilled by the external
cold, how the nose and cheeks and hands look blue, and how the blood,
stagnating in them as in the pendent or lower parts of a corpse,
becomes of a dusky hue; the limbs at the same time getting torpid, so
that they can scarcely be moved, and seem almost to have lost their
vitality. Now they can by no means be so effectually, and especially
so speedily restored to heat and colour and life, as by a new afflux
and appulsion of heat from its source. But how can parts attract in
which the heat and life are almost extinct? Or how should they whose
passages are filled with condensed and frigid blood, admit fresh
aliment--renovated blood--unless they had first got rid of their old
contents? Unless the heart were truly that fountain where life and heat
are restored to the refrigerated fluid, and whence new blood, warm,
imbued with spirits, being sent out by the arteries, that which has
become cooled and effete is forced on, and all the particles recover
their heat which was failing, and their vital stimulus well-nigh

Hence it is that if the heart be unaffected, life and health may be
restored to almost all the other parts of the body; but the heart
being chilled, or smitten with any serious disease, it seems a matter
of necessity that the whole animal fabric should suffer and fall into
decay. When the source is corrupted, there is nothing, as Aristotle
says,[31] which can be of service either to it or aught that depends
on it. And hence, by the way, it may perchance be wherefore grief,
and love, and envy, and anxiety, and all affections of the mind of
a similar kind are accompanied with emaciation and decay, or with
cacochemy and crudity, which engender all manner of diseases and
consume the body of man. For every affection of the mind that is
attended with either pain or pleasure, hope or fear, is the cause of
an agitation whose influence extends to the heart, and there induces
change from the natural constitution, in the temperature, the pulse
and the rest, which impairing all nutrition in its source and abating
the powers at large, it is no wonder that various forms of incurable
disease in the extremities and in the trunk are the consequence,
inasmuch as in such circumstances the whole body labours under the
effects of vitiated nutrition and a want of native heat.

  [31] De Part. Animal. iii.

Moreover, when we see that all animals live through food concocted in
their interior, it is imperative that the digestion and distribution be
perfect; and, as a consequence, that there be a place and receptacle
where the aliment is perfected and whence it is distributed to the
several members. Now this place is the heart, for it is the only organ
in the body which contains blood for the general use; all the others
receive it merely for their peculiar or private advantage, just as the
heart also has a supply for its own especial behoof in its coronary
veins and arteries; but it is of the store which the heart contains
in its auricles and ventricles that I here speak; and then the heart
is the only organ which is so situated and constituted that it can
distribute the blood in due proportion to the several parts of the
body, the quantity sent to each being according to the dimensions
of the artery which supplies it, the heart serving as a magazine or
fountain ready to meet its demands.

Further, a certain impulse or force, as well as an impeller or forcer,
such as the heart, was required to effect this distribution and motion
of the blood; both because the blood is disposed from slight causes,
such as cold, alarm, horror, and the like, to collect in its source,
to concentrate like parts to a whole, or the drops of water spilt upon
a table to the mass of liquid; and then because it is forced from the
capillary veins into the smaller ramifications, and from these into the
larger trunks by the motion of the extremities and the compression of
the muscles generally. The blood is thus more disposed to move from
the circumference to the centre than in the opposite direction, were
there even no valves to oppose its motion; whence that it may leave its
source and enter more confined and colder channels, and flow against
the direction to which it spontaneously inclines, the blood requires
both force and an impelling power. Now such is the heart and the heart
alone, and that in the way and manner already explained.



There are still certain phenomena, which, taken as consequences of
this truth assumed as proven, are not without their use in exciting
belief, as it were, _a posteriore_; and which, although they may seem
to be involved in much doubt and obscurity, nevertheless readily admit
of having reasons and causes assigned for them. The phenomena alluded
to are those that present themselves in connexion with contagions,
poisoned wounds, the bites of serpents and rabid animals, lues
venerea and the like. We sometimes see the whole system contaminated,
though the part first infected remains sound; the lues venerea has
occasionally made its attack with pains in the shoulders and head, and
other symptoms, the genital organs being all the while unaffected; and
then we know that the wound made by a rabid dog having healed, fever
and a train of disastrous symptoms nevertheless supervene. Whence it
appears that the contagion impressed upon or deposited in a particular
part, is by and by carried by the returning current of blood to the
heart, and by that organ is sent to contaminate the whole body.

In tertian fever, the morbific cause seeking the heart in the first
instance, and hanging about the heart and lungs, renders the patient
short-winded, disposed to sighing, indisposed to exertion; because
the vital principle is oppressed and the blood forced into the lungs
and rendered thick, does not pass through their substance, (as I
have myself seen in opening the bodies of those who had died in the
beginning of the attack,) when the pulse is always frequent, small,
and occasionally irregular; but the heat increasing, the matter
becoming attenuated, the passages forced, and the transit made, the
whole body begins to rise in temperature, and the pulse becomes
fuller, stronger--the febrile paroxysm is fully formed, whilst the
preternatural heat kindled in the heart, is thence diffused by the
arteries through the whole body along with the morbific matter, which
is in this way overcome and dissolved by nature.

When we perceive, further, that medicines applied externally exert
their influence on the body just as if they had been taken internally,
the truth we are contending for is confirmed. Colocynth and aloes
[applied externally] move the belly, cantharides excites the urine,
garlic applied to the soles of the feet assists expectoration, cordials
strengthen, and an infinite number of examples of the same kind might
be cited. It will not, therefore, be found unreasonable perchance, if
we say that the veins, by means of their orifices, absorb some of the
things that are applied externally and carry this inwards with the
blood, not otherwise, it may be, than those of the mesentery imbibe
the chyle from the intestines and carry it mixed with the blood to the
liver. For the blood entering the mesentery by the cœliac artery, and
the superior and inferior mesenterics, proceeds to the intestines, from
which, along with the chyle that has been attracted into the veins,
it returns by their numerous ramifications into the vena portæ of the
liver, and from this into the vena cava, and this in such wise that the
blood in these veins has the same colour and consistency as in other
veins, in opposition to what many believe to be the fact. Nor indeed
can we imagine two contrary motions in any capillary system--the chyle
upwards, the blood downwards. This could scarcely take place, and
must be held as altogether improbable. But is not the thing rather
arranged as it is by the consummate providence of nature? For were
the chyle mingled with the blood, the crude with the concocted, in
equal proportions, the result would not be concoction, transmutation,
and sanguification, but rather, and because they are severally active
and passive, a mixture or combination, or medium compound of the two,
precisely as happens when wine is mixed with water and syrup. But when
a very minute quantity of chyle is mingled with a very large quantity
of circulating blood, a quantity of chyle that bears no kind of
proportion to the mass of blood, the effect is the same, as Aristotle
says, as when a drop of water is added to a cask of wine, or the
contrary; the mass does not then present itself as a mixture, but is
still sensibly either wine or water. So in the mesenteric veins of an
animal we do not find either chyme or chyle and blood, blended together
or distinct, but only blood, the same in colour, consistency, and other
sensible properties, as it appears in the veins generally. Still as
there is a certain though small and inappreciable proportion of chyle
or unconcocted matter mingled with this blood, nature has interposed
the liver, in whose meandering channels it suffers delay and undergoes
additional change, lest arriving prematurely and crude at the heart,
it should oppress the vital principle. Hence in the embryo, there is
almost no use for the liver, but the umbilical vein passes directly
through, a foramen or anastomosis existing from the vena portæ, so
that the blood returns from the intestines of the fœtus, not through
the liver, but into the umbilical vein mentioned, and flows at once
into the heart, mingled with the natural blood which is returning from
the placenta; whence also it is that in the development of the fœtus
the liver is one of the organs that is last formed; I have observed
all the members perfectly marked out in the human fœtus, even the
genital organs, whilst there was yet scarcely any trace of the liver.
And indeed at the period when all the parts, like the heart itself
in the beginning, are still white, and save in the veins there is no
appearance of redness, you shall see nothing in the seat of the liver
but a shapeless collection, as it were, of extravasated blood, which
you might take for the effects of a contusion or ruptured vein.

But in the incubated egg there are, as it were, two umbilical vessels,
one from the albumen passing entire through the liver, and going
straight to the heart; another from the yelk, ending in the vena portæ;
for it appears that the chick, in the first instance, is entirely
formed and nourished by the white; but by the yelk after it has come to
perfection and is excluded from the shell; for this part may still be
found in the abdomen of the chick many days after its exclusion, and is
a substitute for the milk to other animals.

But these matters will be better spoken of in my observations on
the formation of the fœtus, where many propositions, the following
among the number, will be discussed: Wherefore is this part formed or
perfected first, that last?--and of the several members: what part
is the cause of another? And many points having special reference to
the heart, such as: Wherefore does it first acquire consistency, and
appear to possess life, motion, sense, before any other part of the
body is perfected, as Aristotle says in his third book, De partibus
Animalium? And so also of the blood: Wherefore does it precede all the
rest? And in what way does it possess the vital and animal principle?
And show a tendency to motion, and to be impelled hither and thither,
the end for which the heart appears to be made? In the same way, in
considering the pulse: Wherefore one kind of pulse should indicate
death, another recovery? And so of all the other kinds of pulse, what
may be the cause and indication of each. So also in the consideration
of crises and natural critical discharges; of nutrition, and especially
the distribution of the nutriment; and of defluxions of every
description. Finally, reflecting on every part of medicine, physiology,
pathology, semeiotics, therapeutics, when I see how many questions can
be answered, how many doubts resolved, how much obscurity illustrated,
by the truth we have declared, the light we have made to shine, I
see a field of such vast extent in which I might proceed so far,
and expatiate so widely, that this my tractate would not only swell
out into a volume, which was beyond my purpose, but my whole life,
perchance, would not suffice for its completion.

In this place, therefore, and that indeed in a single chapter, I shall
only endeavour to refer the various particulars that present themselves
in the dissection of the heart and arteries to their several uses and
causes; for so I shall meet with many things which receive light from
the truth I have been contending for, and which, in their turn, render
it more obvious. And indeed I would have it confirmed and illustrated
by anatomical arguments above all others.

There is but a single point which indeed would be more correctly placed
among our observations on the use of the spleen, but which it will not
be altogether impertinent to notice in this place incidentally. From
the splenic branch which passes into the pancreas, and from the upper
part, arise the posterior coronary, gastric, and gastroepiploic veins,
all of which are distributed upon the stomach in numerous branches and
twigs, just as the mesenteric vessels are upon the intestines; in like
manner, from the inferior part of the same splenic branch, and along
the back of the colon and rectum proceed the hemorrhoidal veins. The
blood returning by these veins, and bringing the cruder juices along
with it, on the one hand from the stomach, where they are thin, watery,
and not yet perfectly chylified; on the other thick and more earthy,
as derived from the fæces, but all poured into this splenic branch,
are duly tempered by the admixture of contraries; and nature mingling
together these two kinds of juices, difficult of coction by reason of
most opposite defects, and then diluting them with a large quantity of
warm blood, (for we see that the quantity returned from the spleen must
be very large when we contemplate the size of its arteries,) they are
brought to the porta of the liver in a state of higher preparation;
the defects of either extreme are supplied and compensated by this
arrangement of the veins.



I do not find the heart as a distinct and separate part in all animals;
some, indeed, such as the zoophytes, have no heart; this is because
these animals are coldest, of no great bulk, of soft texture or of a
certain uniform sameness or simplicity of structure; among the number
I may instance grubs and earth-worms, and those that are engendered of
putrefaction and do not preserve their species. These have no heart, as
not requiring any impeller of nourishment into the extreme parts; for
they have bodies which are connate and homogeneous, and without limbs;
so that by the contraction and relaxation of the whole body they assume
and expel, move and remove the aliment. Oysters, mussels, sponges, and
the whole genus of zoophytes or plant-animals have no heart; for the
whole body is used as a heart, or the whole animal is a heart. In a
great number of animals, almost the whole tribe of insects, we cannot
see distinctly by reason of the smallness of the body; still in bees,
flies, hornets, and the like, we can perceive something pulsating with
the help of a magnifying glass; in pediculi, also, the same thing
may be seen, and as the body is transparent, the passage of the food
through the intestines, like a black spot or stain, may be perceived by
the aid of the same magnifying glass.

In some of the bloodless[32] and colder animals, further, as in
snails, whelks, shrimps, and shell-fish, there is a part which
pulsates--a kind of vesicle or auricle without a heart--slowly indeed,
and not to be perceived save in the warmer season of the year. In these
creatures this part is so contrived that it shall pulsate, as there is
here a necessity for some impulse to distribute the nutritive fluid,
by reason of the variety of organic parts, or of the density of the
substance; but the pulsations occur unfrequently, and sometimes in
consequence of the cold not at all, an arrangement the best adapted
to them as being of a doubtful nature, so that sometimes they appear
to live, sometimes to die; sometimes they show the vitality of an
animal, sometimes of a vegetable. This seems also to be the case with
the insects which conceal themselves in winter, and lie, as it were,
defunct, or merely manifesting a kind of vegetative existence. But
whether the same thing happens in the case of certain animals that have
red blood, such as frogs, tortoises, serpents, swallows, may be made a
question without any kind of impropriety.

  [32] [i.e. Not having red blood.]

In all the larger and warmer, because [red-]blooded animals, there
was need of an impeller of the nutritive fluid, and that perchance
possessing a considerable amount of power. In fishes, serpents,
lizards, tortoises, frogs, and others of the same kind there is a heart
present, furnished with both an auricle and a ventricle, whence it is
perfectly true, as Aristotle has observed,[33] that no [red-]blooded
animal is without a heart, by the impelling power of which the
nutritive fluid is forced, both with greater vigour and rapidity to a
greater distance; it is not merely agitated by an auricle as it is in
lower forms. And then in regard to animals that are yet larger, warmer,
and more perfect, as they abound in blood, which is ever hotter and
more spirituous, and possess bodies of greater size and consistency,
they require a larger, stronger, and more fleshy heart, in order
that the nutritive fluid may be propelled with yet greater force and
celerity. And further, inasmuch as the more perfect animals require a
still more perfect nutrition, and a larger supply of native heat, in
order that the aliment may be thoroughly concocted and acquire the last
degree of perfection, they required both lungs and a second ventricle,
which should force the nutritive fluid through them.

  [33] De Part. Animal. lib. iii.

Every animal that has lungs has therefore two ventricles to its heart,
one right, another left; and wherever there is a right, there also is
there a left ventricle; but the contrary of this does not hold good:
where there is a left there is not always a right ventricle. The left
ventricle I call that which is distinct in office, not in place from
the other, that one namely which distributes the blood to the body at
large, not to the lungs only. Hence the left ventricle seems to form
the principal part of the heart; situated in the middle, more strongly
marked, and constructed with greater care, the heart seems formed for
the sake of the left ventricle, and the right but to minister to it;
for the right neither reaches to the apex of the heart, nor is it
nearly of such strength, being three times thinner in its walls, and in
some sort jointed on to the left, (as Aristotle says;) though indeed it
is of greater capacity, inasmuch as it has not only to supply material
to the left ventricle, but likewise to furnish aliment to the lungs.

It is to be observed, however, that all this is otherwise in the
embryo, where there is not such a difference between the two
ventricles; but as in a double nut, they are nearly equal in all
respects, the apex of the right reaching to the apex of the left, so
that the heart presents itself as a sort of double-pointed cone. And
this is so, because in the fœtus, as already said, whilst the blood
is not passing through the lungs from the right to the left cavities
of the heart, but flowing by the foramen ovale and ductus arteriosus,
directly from the vena cava into the aorta, whence it is distributed
to the whole body, both ventricles have in fact the same office to
perform, whence their equality of constitution. It is only when the
lungs come to be used, and it is requisite that the passages indicated
should be blocked up, that the differences in point of strength and
other things between the two ventricles begin to be apparent: in the
altered circumstances the right has only to throw the blood through the
lungs, whilst the left has to impel it through the whole body.

There are further within the heart numerous braces, so to speak,
fleshy columns and fibrous bands, which Aristotle, in his third book
on Respiration, and the Parts of Animals, entitles nerves. These are
variously extended, and are either distinct or contained in grooves
in the walls and partition, where they occasion numerous pits or
depressions. They constitute a kind of small muscles, which are
superadded and supplementary to the heart, assisting it to execute a
more powerful and perfect contraction, and so proving subservient to
the complete expulsion of the blood. They are in some sort like the
elaborate and artful arrangement of ropes in a ship, bracing the heart
on every side as it contracts, and so enabling it more effectually
and forcibly to expel the charge of blood from its ventricles. This
much is plain, at all events, that some animals have them strongly
marked, others have them less so; and, in all that have them, they are
more numerous and stronger in the left than in the right ventricle;
and whilst some have them in the left, there are yet none present
in the right ventricle. In the human subject, again, these fleshy
columns and braces are more numerous in the left than in the right
ventricle, and they are more abundant in the ventricles than in the
auricles; occasionally, indeed, in the auricles there appear to be none
present whatsoever. In large, more muscular and hardier bodies, as of
countrymen, they are numerous; in more slender frames and in females
they are fewer.

In those animals in which the ventricles of the heart are smooth
within, and entirely without fibres or muscular bands, or anything like
foveæ, as in almost all the smaller birds, the partridge and the common
fowl, serpents, frogs, tortoises, and also fishes, for the major part,
there are no chordæ tendineæ, nor bundles of fibres, neither are there
any tricuspid valves in the ventricles.

Some animals have the right ventricle smooth internally, but the left
provided with fibrous bands, such as the goose, swan, and larger birds;
and the reason here is still the same as elsewhere, as the lungs are
spongy, and loose, and soft, no great amount of force is required to
force the blood through them; hence the right ventricle is either
without the bundles in question, or they are fewer and weaker, not
so fleshy or like muscles; those of the left ventricle, however, are
both stronger and more numerous, more fleshy and muscular, because the
left ventricle requires to be stronger, inasmuch as the blood which
it propels has to be driven through the whole body. And this, too, is
the reason why the left ventricle occupies the middle of the heart,
and has parietes three times thicker and stronger than those of the
right. Hence all animals--and among men it is not otherwise--that
are endowed with particularly strong frames, and that have large and
fleshy limbs at a great distance from the heart, have this central
organ of greater thickness, strength, and muscularity. And this is both
obvious and necessary. Those, on the contrary, that are of softer and
more slender make have the heart more flaccid, softer, and internally
either sparely or not at all fibrous. Consider farther the use of
the several valves, which are all so arranged, that the blood once
received into the ventricles of the heart shall never regurgitate,
once forced into the pulmonary artery and aorta shall not flow back
upon the ventricles. When the valves are raised and brought together
they form a three-cornered line, such as is left by the bite of a
leech; and the more they are forced, the more firmly do they oppose
the passage of the blood. The tricuspid valves are placed, like
gate-keepers, at the entrance into the ventricles, from the venæ cavæ
and pulmonary veins; lest the blood when most forcibly impelled should
flow back; and it is for this reason that they are not found in all
animals; neither do they appear to have been constructed with equal
care in all the animals in which they are found; in some they are more
accurately fitted, in others more remissly or carelessly contrived,
and always with a view to their being closed under a greater or a
slighter force of the ventricle. In the left ventricle, therefore,
and in order that the occlusion may be the more perfect against the
greater impulse, there are only two valves, like a mitre, and produced
into an elongated cone, so that they come together and touch to their
middle; a circumstance which perhaps led Aristotle into the error
of supposing this ventricle to be double, the division taking place
transversely. For the same reason, indeed, and that the blood may
not regurgitate upon the pulmonary veins, and thus the force of the
ventricle in propelling the blood through the system at large come to
be neutralized, it is that these mitral valves excel those of the right
ventricle in size and strength, and exactness of closing. Hence, too,
it is essential that there can be no heart without a ventricle, since
this must be the source and storehouse of the blood. The same law does
not hold good in reference to the brain. For almost no genus of birds
has a ventricle in the brain, as is obvious in the goose and swan, the
brains of which nearly equal that of a rabbit in size; now rabbits
have ventricles in the brain, whilst the goose has none. In like
manner, wherever the heart has a single ventricle, there is an auricle
appended, flaccid, membranous, hollow, filled with blood; and where
there are two ventricles, there are likewise two auricles. On the other
hand, however, some animals have an auricle without any ventricle;
or at all events they have a sac analogous to an auricle; or the vein
itself, dilated at a particular part, performs pulsations, as is seen
in hornets, bees, and other insects, which certain experiments of my
own enable me to demonstrate have not only a pulse, but a respiration
in that part which is called the tail, whence it is that this part is
elongated and contracted now more rarely, now more frequently, as the
creature appears to be blown and to require a larger quantity of air.
But of these things, more in our Treatise on Respiration.

It is in like manner evident that the auricles pulsate, contract, as
I have said before, and throw the blood into the ventricles; so that
wherever there is a ventricle an auricle is necessary, not merely
that it may serve, according to the general belief, as a source and
magazine for the blood: for what were the use of its pulsations had it
nothing to do save to contain? No; the auricles are prime movers of the
blood, especially the right auricle, which is “the first to live, the
last to die,” as already said; whence they are subservient to sending
the blood into the ventricle, which, contracting incontinently, more
readily and forcibly expels the blood already in motion; just as the
ball-player can strike the ball more forcibly and further if he takes
it on the rebound than if he simply threw it. Moreover, and contrary
to the general opinion, since neither the heart nor anything else can
dilate or distend itself so as to draw aught into its cavity during the
diastole, unless like a sponge, it has been first compressed, and as it
is returning to its primary condition; but in animals all local motion
proceeds from, and has its original in the contraction of some part: it
is consequently by the contraction of the auricles that the blood is
thrown into the ventricles, as I have already shown, and from thence,
by the contraction of the ventricles, it is propelled and distributed.
Which truth concerning local motions, and how the immediate moving
organ in every motion of an animal primarily endowed with a motive
spirit (as Aristotle has it,[34]) is contractile; and in what way the
word νευ̑ρον is derived from νεύω, nuto, contraho; and how Aristotle
was acquainted with the muscles, and did not unadvisedly refer all
motion in animals to the nerves, or to the contractile element, and
therefore called those little bands in the heart nerves--all this,
if I am permitted to proceed in my purpose of making a particular
demonstration of the organs of motion in animals from observations in
my possession, I trust I shall be able to make sufficiently plain.

  [34] In the book, de Spiritu, and elsewhere.

But that we may go on with the subject we have in hand, viz. the use of
the auricles in filling the ventricles: we should expect that the more
dense and compact the heart, the thicker its parietes, the stronger
and more muscular must be the auricle to force and fill it, and _vice
versa_. Now this is actually so: in some the auricle presents itself
as a sanguinolent vesicle, as a thin membrane containing blood, as in
fishes, in which the sac that stands in lieu of the auricle, is of such
delicacy and ample capacity, that it seems to be suspended or to float
above the heart; in those fishes in which the sac is somewhat more
fleshy, as in the carp, barbel, tench, and others, it bears a wonderful
and strong resemblance to the lungs.

In some men of sturdier frame and stouter make, the right auricle is
so strong, and so curiously constructed within of bands and variously
interlacing fibres, that it seems to equal the ventricle of the heart
in other subjects; and I must say that I am astonished to find such
diversity in this particular in different individuals. It is to be
observed, however, that in the fœtus the auricles are out of all
proportion large, which is because they are present before the heart
[the ventricular portion] makes its appearance or suffices for its
office even when it has appeared, and they therefore have, as it were,
the duty of the whole heart committed to them, as has already been
demonstrated. But what I have observed in the formation of the fœtus as
before remarked (and Aristotle had already confirmed all in studying
the incubated egg,) throws the greatest light and likelihood upon the
point. Whilst the fœtus is yet in the guise of a soft worm, or, as is
commonly said, in the milk, there is a mere bloody point or pulsating
vesicle, a portion apparently of the umbilical vein, dilated at its
commencement or base; by and by, when the outline of the fœtus is
distinctly indicated, and it begins to have greater bodily consistence,
the vesicle in question having become more fleshy and stronger, and
changed its position, passes into the auricles, over or upon which
the body of the heart begins to sprout, though as yet it apparently
performs no duty; but when the fœtus is farther advanced, when the
bones can be distinguished from the soft parts, and movements take
place, then it has also a heart internately which pulsates, and, as I
have said, throws blood by either ventricle from the vena cava into the

Thus nature, ever perfect and divine, doing nothing in vain, has
neither given a heart where it was not required, nor produced it
before its office had become necessary; but by the same stages in the
development of every animal, passing through the constitutions of all,
as I may say (ovum, worm, fœtus), it acquires perfection in each. These
points will be found elsewhere confirmed by numerous observations on
the formation of the fœtus.

Finally, it was not without good grounds that Hippocrates, in his book,
“De Corde,” intitles it a muscle; as its action is the same, so is its
function, viz. to contract and move something else, in this case, the
charge of blood.

Farther, as in muscles at large, so can we infer the action and use
of the heart from the arrangement of its fibres and its general
structure. All anatomists admit with Galen that the body of the heart
is made up of various courses of fibres running straight, obliquely,
and transversely, with reference to one another; but in a heart which
has been boiled the arrangement of the fibres is seen to be different:
all the fibres in the parietes and septum are circular, as in the
sphincters; those, again, which are in the columnæ extend lengthwise,
and are oblique longitudinally; and so it comes to pass, that when all
the fibres contract simultaneously, the apex of the cone is pulled
towards its base by the columnæ, the walls are drawn circularly
together into a globe, the whole heart in short is contracted, and the
ventricles narrowed; it is therefore impossible not to perceive that,
as the action of the organ is so plainly contraction, its function is
to propel the blood into the arteries.

Nor are we the less to agree with Aristotle in regard to the
sovereignty of the heart; nor are we to inquire whether it receives
sense and motion from the brain? whether blood from the liver? whether
it be the origin of the veins and of the blood? and more of the same
description. They who affirm these propositions against Aristotle,
overlook, or do not rightly understand the principal argument, to the
effect that the heart is the first part which exists, and that it
contains within itself blood, life, sensation, motion, before either
the brain or the liver were in being, or had appeared distinctly, or,
at all events, before they could perform any function. The heart, ready
furnished with its proper organs of motion, like a kind of internal
creature, is of a date anterior to the body: first formed, nature
willed that it should afterwards fashion, nourish, preserve, complete
the entire animal, as its work and dwelling place: the heart, like
the prince in a kingdom, in whose hands lie the chief and highest
authority, rules over all; it is the original and foundation from which
all power is derived, on which all power depends in the animal body.

And many things having reference to the arteries farther illustrate
and confirm this truth. Why does not the arteria venosa pulsate,
seeing that it is numbered among the arteries? Or wherefore is there
a pulse in the vena arteriosa? Because the pulse of the arteries is
derived from the impulse of the blood. Why does an artery differ so
much from a vein in the thickness and strength of its coats? Because
it sustains the shock of the impelling heart and streaming blood.
Hence, as perfect nature does nothing in vain, and suffices under all
circumstances, we find that the nearer the arteries are to the heart,
the more do they differ from the veins in structure; here they are
both stronger and more ligamentous, whilst in extreme parts of the
body, such as the feet and hands, the brain, the mesentery, and the
testicles, the two orders of vessels are so much alike that it is
impossible to distinguish between them with the eye. Now this is for
the following very sufficient reasons: for the more remote vessels are
from the heart, with so much the less force are they impinged upon
by the stroke of the heart, which is broken by the great distance at
which it is given. Add to this, that the impulse of the heart exerted
upon the mass of blood, which must needs fill the trunks and branches
of the arteries, is diverted, divided, as it were, and diminished at
every subdivision; so that the ultimate capillary divisions of the
arteries look like veins, and this not merely in constitution but in
function; for they have either no perceptible pulse, or they rarely
exhibit one, and never save where the heart beats more violently than
wont, or at a part where the minute vessel is more dilated or open than
elsewhere. Hence it happens that at times we are aware of a pulse in
the teeth, in inflammatory tumours, and in the fingers; at another time
we feel nothing of the sort. Hence, too, by this single symptom I have
ascertained for certain that young persons, whose pulses are naturally
rapid, were labouring under fever; in like manner, on compressing the
fingers in youthful and delicate subjects during a feeble paroxysm, I
have readily perceived the pulse there. On the other hand, when the
heart pulsates more languidly, it is often impossible to feel the pulse
not merely in the fingers, but at the wrist, and even at the temple;
this is the case in persons afflicted with lipothymiæ and asphyxia, and
hysterical symptoms, as also in persons of very weak constitution and
in the moribund.

And here surgeons are to be advised that, when the blood escapes with
force in the amputation of limbs, in the removal of tumours, and in
wounds, it constantly comes from an artery; not always per saltum,
however, because the smaller arteries do not pulsate, especially if a
tourniquet has been applied.

And then the reason is the same wherefore the pulmonary artery has
not only the structure of an artery, but wherefore it does not differ
so widely in the thickness of its tunics from the veins as the aorta:
the aorta sustains a more powerful shock from the left ventricle than
the pulmonary artery does from the right; and the tunics of this last
vessel are thinner and softer than those of the aorta in the same
proportion as the walls of the right ventricle of the heart are weaker
and thinner than those of the left ventricle; and in like manner, in
the same degree in which the lungs are softer and laxer in structure
than the flesh and other constituents of the body at large, do the
tunics of the branches of the pulmonary artery differ from the tunics
of the vessels derived from the aorta. And the same proportion in
these several particulars is universally preserved. The more muscular
and powerful men are, the firmer their flesh, the stronger, thicker,
denser, and more fibrous their heart, in the same proportion are the
auricles and arteries in all respects thicker, closer, and stronger.
And again, and on the other hand, in those animals the ventricles of
whose heart are smooth within, without villi or valves, and the walls
of which are thinner, as in fishes, serpents, birds, and very many
genera of animals, in all of them the arteries differ little or nothing
in the thickness of their coats from the veins.

Farther, the reason why the lungs have such ample vessels, both
arteries and veins, (for the capacity of the pulmonary veins exceeds
that of both the crural and jugular vessels,) and why they contain so
large a quantity of blood, as by experience and ocular inspection we
know they do, admonished of the fact indeed by Aristotle, and not led
into error by the appearances found in animals which have been bled
to death,--is, because the blood has its fountain, and storehouse,
and the workshop of its last perfection in the heart and lungs. Why,
in the same way we find in the course of our anatomical dissections
the arteria venosa and left ventricle so full of blood, of the same
black colour and clotted character, too, as that with which the right
ventricle and pulmonary artery are filled, inasmuch as the blood is
incessantly passing from one side of the heart to the other through
the lungs. Wherefore, in fine, the pulmonary artery or vena arteriosa
has the constitution of an artery, and the pulmonary veins or arteriæ
venosæ have the structure of veins; because, in sooth, in function and
constitution, and everything else, the first is an artery, the others
are veins, in opposition to what is commonly believed; and why the
pulmonary artery has so large an orifice, because it transports much
more blood than is requisite for the nutrition of the lungs.

All these appearances, and many others, to be noted in the course of
dissection, if rightly weighed, seem clearly to illustrate and fully
to confirm the truth contended for throughout these pages, and at the
same time to stand in opposition to the vulgar opinion; for it would
be very difficult to explain in any other way to what purpose all is
constructed and arranged as we have seen it to be.

  JOHN RIOLAN, Jun., of Paris

                MOTHER OF LOUIS XIII.



  CAMBRIDGE, 1649.


Some few months ago there appeared a small anatomical and pathological
work from the pen of the celebrated Riolanus, for which, as sent to
me by the author himself, I return him my grateful thanks.[35] I also
congratulate this author on the highly laudable undertaking in which he
has engaged. To demonstrate the seats of all diseases is a task that
can only be achieved under favour of the highest abilities; for surely
he enters on a difficult province who proposes to bring under the
cognizance of the eyes those diseases which almost escape the keenest
understanding. But such efforts become the prince of anatomists; for
there is no science which does not spring from preexisting knowledge,
and no certain and definite idea which has not derived its origin from
the senses. Induced therefore by the subject itself, and the example
of so distinguished an individual, which makes me think lightly of the
labour, I also intend putting to press my Medical Anatomy, or Anatomy
in its Application to Medicine. Not with the purpose, like Riolanus, of
indicating the seats of diseases from the bodies of healthy subjects,
and discussing the several diseases that make their appearance there,
according to the views which others have entertained of them; but that
I may relate from the many dissections I have made of the bodies of
persons diseased, worn out by serious and strange affections, how and
in what way the internal organs were changed in their situation, size,
structure, figure, consistency, and other sensible qualities, from
their natural forms and appearances, such as they are usually described
by anatomists; and in what various and remarkable ways they were
affected. For even as the dissection of healthy and well-constituted
bodies contributes essentially to the advancement of philosophy and
sound physiology, so does the inspection of diseased and cachectic
subjects powerfully assist philosophical pathology. And, indeed, the
physiological consideration of the things which are according to nature
is to be first undertaken by medical men; since that which is in
conformity with nature is right, and serves as a rule both to itself
and to that which is amiss; by the light it sheds, too, aberrations
and affections against nature are defined; pathology then stands out
more clearly; and from pathology the use and art of healing, as well
as occasions for the discovery of many new remedies, are perceived.
Nor could any one readily imagine how extensively internal organs
are altered in diseases, especially chronic diseases, and what
monstrosities among internal parts these diseases engender. So that I
venture to say, that the examination of a single body of one who has
died of tabes or some other disease of long standing, or poisonous
nature, is of more service to medicine than the dissection of the
bodies of ten men who have been hanged.

  [35] Enchiridium Anatomicum et Pathologicum. 12mo, Parisiis, 1648.

I would not have it supposed by this that I in any way disapprove
of the purpose of Riolanus, that learned and skilful anatomist; on
the contrary, I think it deserving of the highest praise, as likely
to be extremely useful to medicine, inasmuch as it illustrates the
physiological branch of this science; but I have thought that it would
scarcely turn out less profitable to the art of healing, did I place
before the eyes of my readers not only the places, but the affections
of these places, illustrating them as I proceed with observations,
and recording the results of my experience derived from my numerous

But it is imperative on me first to dispose of those observations
contained in the work referred to, which bear upon the circulation
of the blood as discovered by me, and which seem to require especial
notice at my hands. For the judgment of such a man, who is indeed the
prince and leader of all the anatomists of the present age, in such
a matter, is not to be lightly esteemed, but is rather to be held of
greater weight and authority, either for praise or blame, than the
commendations or censure of all the world besides.

Riolanus, then, admits our motion of the blood in animals,[36] and
falls in with our conclusions in regard to the circulation; yet not
entirely and avowedly; for he says[37] that the blood contained in
the vena portæ does not circulate like that in the vena cava; and
again he states[38] that there is some blood which circulates, and
that the circulatory vessels are the aorta and vena cava; but then he
denies that the continuations of these trunks have any circulation,
“because the blood is effused into all the parts of the second and
third regions, where it remains for purposes of nutrition; nor does
it return to any greater vessels, unless forcibly drawn back when
there is a great lack of blood in the main channels, or driven by a
fit of passion when it flows to the greater circulatory vessels;” and
shortly afterwards: “thus, as the blood of the veins naturally ascends
incessantly or returns to the heart, so the blood of the arteries
descends or departs from the heart; still, if the smaller veins of
the arms and legs be empty, the blood filling the empty channels in
succession, may descend in the veins, as I have clearly shown,” he
says, “against Harvey and Walæus.” And as the authority of Galen and
daily experience confirm the anastomoses of the arteries and veins,
and the necessity of the circulation of the blood, “you perceive,” he
continues, “how the circulation is effected, without any perturbation
or confusion of fluids and the destruction of the ancient system of

  [36] Enchiridion, lib. iii, cap. 8.

  [37] Ib. lib. ii, cap 21.

  [38] Ib. lib. iii, cap. 8.

These words explain the motives by which this illustrious anatomist
was actuated when he was led partly to admit, partly to deny the
circulation of the blood; and why he only ventures on an undecided
and inconclusive opinion of the subject; his fear is lest it destroy
the ancient medicine. Not yielding implicitly to the truth, which it
appears he could not help seeing, but rather guided by caution, he
fears speaking plainly out, lest he offend the ancient physic, or
perhaps seem to retract the physiological doctrines he supports in his
Anthropology. The circulation of the blood does not shake, but much
rather confirms the ancient medicine; though it runs counter to the
physiology of physicians, and their speculations upon natural subjects,
and opposes the anatomical doctrine of the use and action of the heart
and lungs, and rest of the viscera. That this is so shall readily be
made to appear, both from his own words and avowal, and partly also
from what I shall supply; viz. that the whole of the blood, wherever
it be in the living body, moves and changes its place, not merely that
which is in the larger vessels and their continuations, but that also
which is in their minute subdivisions, and which is contained in the
pores or interstices of every part; that it flows from and back to the
heart ceaselessly and without pause, and could not pause for ever so
short a time without detriment, although I admit that occasionally, and
in some places, its motion is quicker or slower.[39]

  [39] Vide Chapter III.

In the first place, then, our learned anatomist only denies that the
contents of the branches in continuation of the vena portæ circulate;
but he could neither oppose nor deny this, did he not conceal from
himself the force of his own arguments; for he says in his Third Book,
chap. viii., “If the heart at each pulsation admits a drop of blood
which it throws into the aorta, and in the course of an hour makes
two thousand beats, it is a necessary consequence that the quantity
of blood transmitted must be great.” He is farther forced to admit as
much in reference to the mesentery, when he sees that far more than
single drops of blood are sent into the cœliac and mesenteric arteries
at each pulsation; so that there must either be some outlet for the
fluid, of magnitude commensurate with its quantity, or the branches
of the vena portæ must give way. Nor can the explanation that is had
recourse to with a view of meeting the difficulty, viz. that the blood
of the mesentery ebbs and flows by the same channels, after the manner
of Euripus, be received as either probable or possible. Neither can
the reflux from the mesentery be effected by those passages and that
system of translation, by which he will have it to disgorge itself
into the aorta; this were against the force of the existing current,
and by a contrary motion; nor can anything like pause or alternation
be admitted, where there is very certainly an incessant influx: the
blood sent into the mesentery must as inevitably go elsewhere as that
which is poured into the heart. And this is obvious; were it otherwise,
indeed, everything like a circulation might be overturned upon the same
showing and by the same subterfuge; it might just as well be said that
the blood contained in the left ventricle of the heart is propelled
into the aorta during the systole, and flows back to it during the
diastole, the aorta disgorging itself into the ventricle, precisely as
the ventricle has disgorged itself into the aorta. There would thus be
circulation neither in the heart nor in the mesentery, but an alternate
flux and reflux,--a useless labour, as it seems. If, therefore, and
for the reason assigned and approved by him, a circulation through
the heart be argued for as a thing necessary, the argument has
precisely the same force when applied to the mesentery: if there be no
circulation in the mesentery, neither is there any in the heart; for
both affirmations, this in reference to the heart, that in reference to
the mesentery, merely changing the words, stand or fall together, by
force of the very same arguments.

He says: “The sigmoid valves prevent regurgitation into the heart; but
there are no valves in the mesentery.” To this I reply, that the thing
is not so; for there is a valve in the splenic vein, and sometimes
also in other veins. And besides, valves are not met with universally
in veins; there are few or none in the deep-seated veins of the
extremities, but many in the subcutaneous branches. For where the blood
is flowing naturally from smaller into greater branches, into which
it is disposed to enter, the pressure of the circumjacent muscles is
enough, and more than enough to prevent all retrograde movement, and
it is forced on where the way lies open; in such circumstances, what
use were there for valves? But the quantity of blood that is forced
into the mesentery by each stroke of the heart, may be estimated in
the same way as you estimate the quantity impelled into the hand when
you bind a ligature with medium tightness about the wrist: if in so
many beats the vessels of the hand become distended, and the whole
extremity swells, you will find, that much more than a single drop of
blood has entered with each pulse, and which cannot return, but must
remain to fill the hand and increase its size. But analogy permits us
to say, that the same thing takes place in reference to the mesentery
and its vessels, in an equal degree at least, if not in a greater
degree, seeing that the vessels of the mesentery are considerably
larger than those of the carpus. And if any one will but think on the
difficulty that is experienced with all the aid supplied by compresses,
bandages, and a multiplied apparatus, in restraining the flow of blood
from the smallest artery when wounded, with what force it overcomes
all obstacles and soaks through the whole apparatus, he will scarcely,
I imagine, think it likely that there can be any retrograde motion
against such an impulse and influx of blood, any retrograde force to
meet and overcome a direct force of such power. Turning over these
things in his mind, I say, no one will ever be brought to believe
that the blood from the branches of the vena portæ can possibly make
its way by the same channels against an influx by the artery of such
impetuosity and force, and so unload the mesentery.

Moreover, if the learned anatomist does not think that the blood is
moved and changed by a circular motion, but that the same fluid always
stagnates in the channels of the mesentery, he appears to suppose
that there are two descriptions of blood, serving different uses and
ends; that the blood of the vena portæ, and that of the vena cava are
dissimilar in constitution, seeing that the one requires a circulation
for its preservation, the other requires nothing of the kind; which
neither appears on the face of the thing, nor is its truth demonstrated
by him. Our author then refers to “A fourth order of mesenteric
vessels, the lacteal vessels, discovered by Asellius,”[40] and having
mentioned these, he seems to infer that they extract all the nutriment
from the intestines, and transfer this to the liver, the workshop of
the blood, whence, having been concocted and changed into blood, (so
he says in his third book, chapter the 8th), the blood is transferred
from the liver to the right ventricle of the heart. “Which things
premised,” he continues,[41] “all the difficulties which were formerly
experienced in regard to the distribution of the chyle and blood by the
same channel come to an end; for the lacteal veins carry the chyle to
the liver, and as these canals are distinct, so may they be severally
obstructed.” But truly I would here ask: how this milky fluid can be
poured into and pass through the liver, and how from thence gain the
vena cava and the ventricle of the heart when our author denies that
the blood of the vena portæ passes through the liver, and that so a
circulation is established? I pause for a reply. I would fain know how
such a thing can be shown to be probable; especially when the blood
appears to be both more spirituous or subtile and penetrating than
the chyle or milk contained in these lacteal vessels, and is further
impelled by the pulsations of the arteries that it may find a passage
by other channels.

  [40] Enchiridion, lib. ii, cap. 18.

  [41] Ibid.

Our learned author mentions a certain tract of his on the Circulation
of the Blood: I wish I could obtain a sight of it; perhaps I might
retract. But had the learned writer been so disposed, I do not see
but that having admitted the circular motion of the blood,[42] all
the difficulties which were formerly felt in connexion with the
distribution of the chyle and the blood by the same channels are
brought to an equally satisfactory solution; so much so indeed that
there would be no necessity for inquiring after or laying down any
separate vessels for the chyle. Even as the umbilical veins absorb the
nutritive juices from the fluids of the egg and transport them for
the nutrition and growth of the chick, in its embryo state, so do the
meseraic veins suck up the chyle from the intestines and transfer it to
the liver; and why should we not maintain that they perform the same
office in the adult? For all the mooted difficulties vanish when we
cease to suppose two contrary motions in the same vessels, and admit
but one and the same continuous motion in the mesenteric vessels from
the intestines to the liver.

  [42] Enchiridion, lib. iii, cap. 8: “The blood incessantly and
  naturally ascends or flows back to the heart in the veins, as in the
  arteries it descends or departs from the heart.”

I shall elsewhere state my views of the lacteal veins when I treat of
the milk found in different parts of new-born animals, especially of
the human subject; for it is met with in the mesentery and all its
glands, in the thymus, in the axillæ, also in the breasts of infants.
This milk the midwifes are in the habit of pressing out, for the
health, as they believe, of the infants. But it has pleased the learned
Riolanus, not only to take away circulation from the blood contained in
the mesentery; he affirms that neither do the vessels in continuation
of the vena cava, nor the arteries, nor any of the parts of the
second and third regions, admit of circulation, so that he entitles
and enumerates as circulating vessels the vena cava and aorta only.
For this he appears to me to give a very indifferent reason:[43] “The
blood,” he says, “effused into all the parts of the second and third
regions, remains there for their nutrition; nor does it return to the
great vessels, unless forcibly drawn back by an extreme dearth of blood
in the great vessels, nor, unless carried by an impulse, does it flow
to the circulatory vessels.”

  [43] Enchirid. lib. iii, cap. 8.

That so much of the blood must remain as is appropriated to the
nutrition of the tissues, is matter of necessity; for it cannot nourish
unless it be assimilated and become coherent, and form substance in
lieu of that which is lost; but that the whole of the blood which flows
into a part should there remain, in order that so small a portion
should undergo transformation, is nowise necessary; for no part uses so
much blood for its nutrition as is contained in its arteries, veins,
and interstices. Nor because the blood is continually coming and going
is it necessary to suppose that it leaves nothing for nutriment behind
it. Consequently it is by no means necessary that the whole remain
in order that nutrition be effected. But our learned author, in the
same book, where he affirms so much, appears almost everywhere else to
assert the contrary. In that paragraph especially where he describes
the circulation in the brain, he says: “And the brain by means of
the circulation sends back blood to the heart, and thus refrigerates
the organ.” And in the same way are all the more remote parts said
to refrigerate the heart; thus in fevers, when the præcordia are
scorched and burn with febrile heat, patients baring their limbs and
casting off the bedclothes, seek to cool their heart; and the blood
generally, tempered and cooled down, as our learned author states it to
be with reference to the brain in particular, returns by the veins and
refrigerates the heart. Our author, therefore, appears to insinuate a
certain necessity for a circulation from every part, as well as from
the brain, in opposition to what he had before said in very precise
terms. But then he cautiously and ambiguously asserts, that the
blood does not return from the parts composing the second and third
regions, unless, as he says, it is drawn by force, and through a signal
deficiency of blood in the larger vessels, &c., which is most true if
these words be rightly understood; for by the larger vessels, in which
the deficiency is said to cause the reflux, I think he must be held to
mean the veins not the arteries; for the arteries are never emptied,
save into the veins or interstices of parts, but are incessantly filled
by the strokes of the heart; but in the vena cava and other returning
channels, in which the blood glides rapidly on, hastening to the heart,
there would speedily be a great deficiency of blood did not every part
incessantly restore the blood that is incessantly poured into it. Add
to this, that by the impulse of the blood which is forced with each
stroke into every part of the second and third regions, that which
is contained in the pores or interstices is urged into the smaller
veins, from which it passes into larger vessels, its motion assisted
besides by the motion and pressure of circumjacent parts; for from
every containing thing compressed and constringed, contained matters
are forced out. And thus it is that by the motions of the muscles
and extremities, the blood contained in the minor vessels is forced
onwards and delivered into the larger trunks. But that the blood is
incessantly driven from the arteries into every part of the body,
there gives a pulse and never flows back in these channels, cannot
be doubted, if it be admitted that with each pulse of the heart all
the arteries are simultaneously distended by the blood sent into
them; and as our learned author himself allows that the diastole of
the arteries is occasioned by the systole of the heart, and that the
blood once out of the heart can never get back into the ventricles by
reason of the opposing valves; if I say, our learned author believes
that these things are so, it will be as manifestly true with regard to
the force and impulse by which the blood contained in the vessels is
propelled into every part of every region of the body. For wheresoever
the arteries pulsate, so far must the impulse and influx extend, and
therefore is the impulse felt in every part of each several region;
for there is a pulse everywhere, to the very points of the fingers and
under the nails, nor is there any part of the body where the shooting
pain that accompanies each pulse of the artery, and the effort made to
effect a solution of the continuity is not experienced when it is the
seat of a phlegmon or furuncle.

But, further, that the blood contained in the pores of the living
tissues returns to the heart, is manifest from what we observe in the
hands and feet. For we frequently see the hands and feet, in young
persons especially, during severe weather, become so cold that to the
touch they feel like ice, and they are so benumbed and stiffened that
they seem scarcely to retain a trace of sensibility or to be capable
of any motion; still are they all the while surcharged with blood, and
look red or livid. Yet can the extremities be warmed in no way, save
by circulation; the chilled blood, which has lost its spirit and heat,
being driven out, and fresh, warm, and vivified blood flowing in by
the arteries in its stead, which fresh blood cherishes and warms the
parts, and restores to them sense and motion; nor could the extremities
be restored by the warmth of a fire or other external heat, any more
than those of a dead body could be so recovered: they are only brought
to life again, as it were, by an influx of internal warmth. And this
indeed is the principal use and end of the circulation; it is that
for which the blood is sent on its ceaseless course, and to exert its
influence continually in its circuit, to wit, that all parts dependent
on the primary innate heat may be retained alive, in their state of
vital and vegetative being, and apt to perform their functions; whilst,
to use the language of physiologists, they are sustained and actuated
by the inflowing heat and vital spirits. Thus, by the aid of two
extremes, viz. cold and heat, is the temperature of the animal body
retained at its mean. For as the air inspired tempers the too great
heat of the blood in the lungs and centre of the body, and effects the
expulsion of suffocating fumes, so in its turn does the hot blood,
thrown by the arteries into all parts of the body, cherish and nourish
and keep them in life, defending them from extinction through the power
of external cold.

It would, therefore, be in some sort unfair and extraordinary did
not every particle composing the body enjoy the advantages of the
circulation and transmutation of the blood; the ends for which the
circulation was mainly established by nature would no longer be
effected. To conclude then: you see how circulation may be accomplished
without confusion or admixture of humours, through the whole body, and
each of its individual parts, in the smaller as well as in the larger
vessels; and all as matter of necessity and for the general advantage;
without circulation, indeed, there would be no restoration of chilled
and exhausted parts, no continuance of these in life; since it is
apparent enough that the whole influence of the preservative heat
comes by the arteries, and is the work of the circulation.

It, therefore, appears to me that the learned Riolanus speaks rather
expediently than truly, when in his Enchiridion he denies a circulation
to certain parts; it would seem as though he had wished to please the
mass, and oppose none; to have written with such a bias rather than
rigidly and in behalf of the simple truth. This is also apparent when
he would have the blood to make its way into the left ventricle through
the septum of the heart, by certain invisible and unknown passages,
rather than through those ample and abundantly pervious channels,
the pulmonary vessels, furnished with valves, opposing all reflux
or regurgitation. He informs us that he has elsewhere discussed the
reasons of the impossibility or inconvenience of this: I much desire
to see his disquisition. It would be extraordinary, indeed, were the
aorta and pulmonary artery, with the same dimensions, properties,
and structure, not to have the same functions. But it would be more
wonderful still were the whole tide of the blood to reach the left
ventricle by a set of inscrutable passages of the septum, a tide which,
in quantity, must correspond, first to the influx from the vena cava
into the right side of the heart, and next to the efflux from the left,
both of which require such ample conduits. But our author has adduced
these matters inconsistently, for he has established the lungs as an
emunctory or passage from the heart;[44] and he says: “The lung is
affected by the blood which passes through it, the sordes flowing along
with the blood.” And, again: “The lungs receive injury from distempered
and ill-conditioned viscera; these deliver an impure blood to the
heart, which it cannot correct except by multiplied circulations.” In
the same place, he further proceeds, whilst speaking against Galen of
blood-letting in peri-pneumonia and the communication of the veins:

  [44] Lib. iii, cap. 6.

“Were it true that the blood naturally passed from the right ventricle
of the heart to the lungs, that it might be carried into the left
ventricle and from thence into the aorta; and were the circulation of
the blood admitted, who does not see that in affections of the lungs
the blood would flow to them in larger quantity and would oppress them,
unless it were taken away, first, freely, and then in repeated smaller
quantities in order to relieve them, which indeed was the advice of
Hippocrates, who, in affections of the lungs takes away blood from
every part--the head, nose, tongue, arms and feet, in order that its
quantity may be diminished and a diversion effected from the lungs; he
takes away blood till the body is almost bloodless. Now admitting the
circulation, the lungs are most readily depleted by opening a vein;
but rejecting it, I do not see how any revulsion of the blood can be
accomplished by this means; for did it flow back by the pulmonary
artery upon the right ventricle, the sigmoid valves would oppose its
entrance, and any escape from the right ventricle into the vena cava
is prevented by the tricuspid valves. The blood, therefore, is soon
exhausted when a vein is opened in the arm or foot, if we admit the
circulation; and the opinion of Fernelius is at the same time upset by
this admission, viz. that in affections of the lungs it is better to
bleed from the right than the left arm; because the blood cannot flow
backwards into the vena cava unless the two barriers situated in the
heart be first broken down.”

He adds yet further in the same place:[45] “If the circulation of the
blood be admitted, and it be acknowledged that this fluid generally
passes through the lungs, not through the middle partition of the
heart, a double circulation becomes requisite; one effected through the
lungs, in the course of which the blood quitting the right ventricle
of the heart passes through the lungs in order that it may arrive at
the left ventricle; leaving the heart on the one hand, therefore, the
blood speedily returns to it again; another and longer circulation
proceeding from the left ventricle of the heart performs the circuit of
the whole body by the arteries, and by the veins returns to the right
side of the heart.”

  [45] Lib. iii, cap. 6.

The learned anatomist might here have added a third and extremely short
circulation, viz. from the left to the right ventricle of the heart,
with that blood which courses through the coronary arteries and veins,
and by their ramifications is distributed to the body, walls, and
septum of the heart.

“He who admits one circulation,” proceeds our author, “cannot repudiate
the other;” and he might, as it appears, have added, “the third.” For
why should the coronary arteries of the heart pulsate, if it were not
to force on the blood by their pulsations? and why should there be
coronary veins, the end and office of all veins being to receive the
blood brought by the arteries, were it not to deliver and discharge the
blood sent into the substance of the heart? In this consideration let
it be remembered that a valve is very commonly found at the orifice of
the coronary vein, as our learned author himself admits,[46] preventing
all ingress, but offering no obstacle to the egress of the blood. It
therefore seems that he cannot do otherwise than admit this third
circulation, who acknowledges a general circulation through the body,
and that the blood also passes through the lungs and the brain.[47]
Nor, indeed, can he deny a similar circulation to every other part of
every other region. The blood flowing in under the influence of the
arterial pulse, and returning by the veins, every particle of the body
has its circulation.

  [46] Lib. iii, cap. 9.

  [47] Lib. iv, cap. 2.

From the words of our learned writer quoted above, consequently, his
opinion may be gathered both of the general circulation, and then of
the circulation through the lungs and the several parts of the body;
for he who admits the first, manifestly cannot refuse to acknowledge
the others. How indeed could he who has repeatedly asserted a
circulation through the general system and the greater vessels, deny a
circulation in the branches continuous with these vessels, or in the
several parts of the second and third regions? as if all the veins,
and those he calls greater circulatory vessels, were not enumerated
by every anatomist, and by himself, as being within the second region
of the body. Is it possible that there can be a circulation which is
universal, and which yet does not extend through every part? Where
he denies it, then, he does so hesitatingly, and vacillates between
negations, giving us mere words. Where he asserts the circulation, on
the contrary, he speaks out heartily, and gives sufficient reasons,
as becomes a philosopher; and then, when he relies on this opinion
in a particular instance, he delivers himself like an experienced
physician and honest man, and, in opposition to Galen and his favourite
Fernelius, advises blood-letting as the chief remedy in dangerous
diseases of the lungs.

No learned man and Christian, having doubts in such a cause, would have
recommended his experience to posterity, to the imminent risk, and even
loss of human life; neither would he, without very sufficient reasons,
have repudiated the authority of Galen and Fernelius, which has usually
such weight with him. Whatever he has denied in the circulation of the
blood, therefore, whether with reference to the mesentery or any other
part, and with an eye to the lacteal veins or the ancient system of
physic, or any other consideration, must be ascribed to his courtesy
and modesty, and is to be excused.

Thus far, I think, it appears plain enough, from the very words and
arguments of our author, that there is a circulation everywhere; that
the blood, wherever it is, changes its place, and by the veins returns
to the heart; so that our learned author seems to be of the same
opinion as myself. It would therefore be labour in vain, did I here
quote at greater length the various reasons which I have consigned in
my work on the Motion of the Blood, in confirmation of my opinions, and
which are derived from the structure of the vessels, the position of
the valves, and other matters of experience and observation; and this
the more, as I have not yet seen the treatise on the Circulation of the
Blood of the learned writer; nor, indeed, have I yet met with a single
argument of his, or more than his simple negation, which would lead
me to see wherefore he should reject a circulation which he admits as
universal, in certain parts, regions, and vessels.

It is true that by way of subterfuge he has recourse to an anastomosis
of the vessels on the authority of Galen, and the evidence of daily
experience. But so distinguished a personage, an anatomist so expert,
so inquisitive, and careful, should first have shown anastomoses
between the larger arteries and larger veins, and these, both
obvious and ample, having mouths in relation with such a torrent
as is constituted by the whole mass of the blood, and larger than
the capacity of the continuous branches, (from which he takes away
all circulation,) before he had rejected those that are familiarly
known, that are more likely and more open; he ought to have clearly
shown us where these anastomoses are, and how they are fashioned,
whether they be adapted only to permit the access of the blood into
the veins, and not to allow of its regurgitation, in the same way
as we see the ureters connected with the urinary bladder, or in
what other manner things are contrived. But--and here I speak over
boldly perhaps--neither our learned author himself, nor Galen, nor
any experience, has ever succeeded in making such anastomoses as he
imagines, sensible to the eye.

I have myself pursued this subject of the anastomosis with all the
diligence I could command, and have given not a little both of time
and labour to the inquiry; but I have never succeeded in tracing any
connexion between arteries and veins by a direct anastomosis of their
orifices. I would gladly learn of those who give so much to Galen,
how they dare swear to what he says. Neither in the liver, spleen,
lungs, kidneys, nor any other viscus, is such a thing as an anastomosis
to be seen; and by boiling, I have rendered the whole parenchyma of
these organs so friable that it could be shaken like dust from the
fibres, or picked away with a needle, until I could trace the fibres
of every subdivision, and see every capillary filament distinctly. I
can therefore boldly affirm, that there is neither any anastomosis of
the vena portæ with the cava, of the arteries with the veins, or of
the capillary ramifications of the biliary ducts, which can be traced
through the entire liver, with the veins. This alone may be observed in
the recent liver: all the branches of the vena cava ramifying through
the convexity of the liver, have their tunics pierced with an infinity
of minute holes as is a sieve, and are fashioned to receive the blood
in its descent. The branches of the porta are not so constituted, but
simply spread out in subdivisions; and the distribution of these two
vessels is such, that whilst the one runs upon the convexity, the other
proceeds along the concavity of the liver to its outer margin, and all
the while without anastomosing.

In three places only do I find anything that can be held equivalent to
an anastomosis. From the carotids, as they are creeping over the base
of the brain, numerous interlaced fibres arise, which afterwards form
the choroid plexus, and passing through the lateral ventricles, finally
unite and terminate in the third sinus, which performs the office of
a vein. In the spermatic vessels, commonly called vasa præparantia,
certain minute arteries proceeding from the great artery adhere to the
venæ præparantes, which they accompany, and are at length taken in and
included within their coats, in such a way that they seem to have a
common ending, so that where they terminate on the upper portion of
the testis, on that cone-shaped process called the corpus varicosum et
pampiniforme, it is altogether uncertain whether we are to regard their
terminations as veins, or as arteries, or as both. In the same way are
the ultimate ramifications of the arteries which run to the umbilical
vein, lost in the tunics of this vessel.

What doubt can there be, if by such channels the great arteries,
distended by the stream of blood sent into them, are relieved of so
great and obvious a torrent, but that nature would not have denied
distinct and visible passages, vortices, and estuaries, had she
intended to divert the whole current of the blood, and had wished in
this way to deprive the lesser branches and the solid parts of all the
benefit of the influx of that fluid?

Finally, I shall quote this single experiment, which appears to me
sufficient to clear up all doubts about the anastomoses, and their
uses, if any exist, and to set at rest the question of a passage of the
blood from the veins to the arteries, by any special channels, or by

Having laid open the thorax of an animal, and tied the vena cava
near the heart, so that nothing shall pass from that vessel into its
cavities, and immediately afterwards, having divided the carotid
arteries on both sides, the jugular veins being left untouched; if the
arteries be now perceived to become empty but not the veins, I think
it will be manifest that the blood does nowhere pass from the veins
into the arteries except through the ventricles of the heart. Were
it not so, as observed by Galen, we should see the veins as well as
the arteries emptied in a very short time, by the efflux from their
corresponding arteries.

For what further remains, oh Riolanus! I congratulate both myself
and you: myself, for the opinion with which you have graced my
Circulation; and you, for your learned, polished, and terse production,
than which nothing more elegant can be imagined. For the favour you
have done me in sending me this work, I feel most grateful, and I
would gladly, as in duty bound, proclaim my sense of its merits, but
I confess myself unequal to the task; for I know that the Enchiridion
bearing the name of Riolanus inscribed upon it, has thereby more of
honour conferred upon it than it can derive from any praise of mine,
which nevertheless I would yield without reserve. The famous book will
live for ever; and when marble shall have mouldered, will proclaim to
posterity the glory that belongs to your name. You have most happily
conjoined anatomy with pathology, and have greatly enriched the subject
with a new and most useful osteology. Proceed in your worthy career,
most illustrious Riolanus, and love him who wishes that you may enjoy
both happiness and length of days, and that all your admirable works
may conduce to your eternal fame.



It is now many years, most learned Riolanus, since, with the aid of
the press, I published a portion of my work. But scarce a day, scarce
an hour, has passed since the birth-day of the Circulation of the
blood, that I have not heard something for good or for evil said of
this my discovery. Some abuse it as a feeble infant, and yet unworthy
to have seen the light; others, again, think the bantling deserves
to be cherished and cared for; these oppose it with much ado, those
patronize it with abundant commendation; one party holds that I have
completely demonstrated the circulation of the blood by experiment,
observation, and ocular inspection, against all force and array of
argument; another thinks it scarcely yet sufficiently illustrated--not
yet cleared of all objections. There are some, too, who say that I
have shown a vainglorious love of vivisections, and who scoff at and
deride the introduction of frogs and serpents, flies, and others of the
lower animals upon the scene, as a piece of puerile levity, not even
refraining from opprobrious epithets.

To return evil speaking with evil speaking, however, I hold to be
unworthy in a philosopher and searcher after truth; I believe that I
shall do better and more advisedly if I meet so many indications of
ill breeding with the light of faithful and conclusive observation. It
cannot be helped that dogs bark and vomit their foul stomachs, or that
cynics should be numbered among philosophers; but care can be taken
that they do not bite or inoculate their mad humours, or with their
dogs’ teeth gnaw the bones and foundations of truth.

Detractors, mummers, and writers defiled with abuse, as I resolved with
myself never to read them, satisfied that nothing solid or excellent,
nothing but foul terms, was to be expected from them, so have I held
them still less worthy of an answer. Let them consume on their own ill
nature; they will scarcely find many well-disposed readers, I imagine,
nor does God give that which is most excellent and chiefly to be
desired--wisdom, to the wicked; let them go on railing, I say, until
they are weary, if not ashamed.

If for the sake of studying the meaner animals you should even enter
the bakehouse with Heraclitus, as related in Aristotle, I bid you
approach; for neither are the immortal Gods absent here, and the great
and almighty Father is sometimes most visible in His lesser, and to the
eye least considerable works.[48]

  [48] To those who hesitated to visit him in his kiln or bakehouse
  (ἱπνω, which some have said should be ἱππω, rendered a dunghill)
  Heraclitus addressed the words in the text. Aristotle, who quotes
  them, has been defending the study of the lower animals.

In my book on the Motion of the Heart and Blood in Animals, I have
only adduced those facts from among many other observations, by which
either errors were best refuted, or truth was most strongly supported;
I have left many proofs, won by dissection and appreciable to sense,
as redundant and unnecessary; some of these, however, I now supply in
brief terms, for the sake of the studious, and those who have expressed
their desire to have them.

The authority of Galen is of such weight with all, that I have seen
several hesitate greatly with that experiment before them, in which
the artery is tied upon a tube placed within its cavity; and by which
it is proposed to prove that the arterial pulse is produced by a power
communicated from the heart through the coats of the arteries, and not
from the shock of the blood contained within them; and thence, that the
arteries dilate as bellows, are not filled as sacs. This experiment is
spoken of by Vesalius, the celebrated anatomist; but neither Vesalius
nor Galen says that he had tried the experiment, which, however, I
did. Vesalius only prescribes, and Galen advises it, to those anxious
to discover the truth, and for their better assurance, not thinking
of the difficulties that attend its performance, nor of its futility
when done; for indeed, although executed with the greatest skill,
it supplies nothing in support of the opinion which maintains that
the coats of the vessel are the cause of the pulse; it much rather
proclaims that this is owing to the impulse of the blood. For the
moment you have thrown your ligature around the artery upon the reed or
tube, immediately, by the force of the blood thrown in from above, it
is dilated beyond the circle of the tube, by which the flow is impeded,
and the shock is broken; so that the artery which is tied only pulsates
obscurely, being now cut off from the full force of the blood that
flows through it, the shock being reverberated, as it were, from that
part of the vessel which is above the ligature; but if the artery below
the ligature be now divided, the contrary of what has been maintained
will be apparent, from the spurting of the blood impelled through the
tube; just as happens in the cases of aneurism, referred to in my book
on the Motion of the Blood, which arise from an erosion of the coats of
the vessel, and when the blood is contained in a membranous sac, formed
not by the coats of the vessel dilated, but preternaturally produced
from the surrounding tissues and flesh. The arteries beyond an aneurism
of this kind will be felt beating very feebly, whilst in those above
it and in the swelling itself the pulse will be perceived of great
strength and fulness. And here we cannot imagine that the pulsation
and dilatation take place by the coats of the arteries, or any power
communicated to the walls of the sac; they are plainly due to the shock
of the blood.

But that the error of Vesalius, and the inexperience of those who
assert their belief that the part below the tube does not pulsate when
the ligature is tied, may be made the more apparent, I can state, after
having made the trial, that the inferior part will continue to pulsate
if the experiment be properly performed; and whilst they say that when
you have undone the ligature the inferior arteries begin again to
pulsate, I maintain that the part below beats less forcibly when the
ligature is untied than it did when the thread was still tight. But the
effusion of blood from the wound confuses everything, and renders the
whole experiment unsatisfactory and nugatory, so that nothing certain
can be shown, by reason, as I have said, of the hemorrhage. But if, as
I know by experience, you lay bare an artery, and control the divided
portion by the pressure of your fingers, you may try many things at
pleasure by which the truth will be made to appear. In the first place,
you will feel the blood coming down in the artery at each pulsation,
and visibly dilating the vessel. You may also at will suffer the blood
to escape, by relaxing the pressure, and leaving a small outlet; and
you will see that it jets out with each stroke, with each contraction
of the heart, and with each dilatation of the artery, as I have said
in speaking of arteriotomy, and the experiment of perforating the
heart. And if you suffer the efflux to go on uninterruptedly, either
from the simple divided artery or from a tube inserted into it, you
will be able to perceive by the sight, and if you apply your hand, by
the touch likewise, every character of the stroke of the heart in the
jet; the rhythm, order, intermission, force, &c., of its pulsations,
all becoming sensible there, no otherwise than would the jets from a
syringe, pushed in succession and with different degrees of force,
received upon the palm of the hand, be obvious to sight and touch. I
have occasionally observed the jet from a divided carotid artery to be
so forcible, that, when received on the hand, the blood rebounded to
the distance of four or five feet.

But that the question under discussion, viz. that the pulsific power
does not proceed from the heart by the coats of the vessels, may be
set in yet a clearer light, I beg here to refer to a portion of the
descending aorta, about a span in length, with its division into the
two crural trunks, which I removed from the body of a nobleman, and
which is converted into a bony tube; by this hollow tube, nevertheless,
did the arterial blood reach the lower extremities of this nobleman
during his life, and cause the arteries in these to beat; and yet the
main trunk was precisely in the same condition as is the artery in the
experiment of Galen, when it is tied upon a hollow tube; where it was
converted into bone it could neither dilate nor contract like bellows,
nor transmit the pulsific power from the heart to the inferior vessels;
it could not convey a force which it was incapable of receiving through
the solid matter of the bone. In spite of all, however, I well remember
to have frequently noted the pulse in the legs and feet of this patient
whilst he lived, for I was myself his most attentive physician, and he
my very particular friend. The arteries in the inferior extremities of
this nobleman must therefore and of necessity have been dilated by the
impulse of the blood like flaccid sacs, and not have expanded in the
manner of bellows through the action of their tunics. It is obvious,
that whether an artery be tied over a hollow tube, or its tunics be
converted into a bony and unyielding canal, the interruption to the
pulsific power in the inferior part of the vessel must be the same.

I have known another instance in which a portion of the aorta near
the heart was found converted into bone, in the body of a nobleman, a
man of great muscular strength. The experiment of Galen, therefore,
or, at all events, a state analogous to it, not effected on purpose
but encountered by accident, makes it sufficiently to appear, that
compression or ligature of the coats of an artery does not interfere
with the pulsative properties of its derivative branches; and indeed,
if the experiment which Galen recommends were properly performed by
any one, its results would be found in opposition to the views which
Vesalius believed they would support.

But we do not therefore deny everything like motion to the tunics of
the arteries; on the contrary, we allow them the same motions which we
concede to the heart, viz. a diastole, and a systole or return from the
distended to the natural state; this much we believe to be effected by
a power inherent in the coats themselves. But it is to be observed,
that they are not both dilated and contracted by the same, but by
different causes and means; as may be observed of the motions of all
parts, and of the ventricle of the heart itself, which is distended by
the auricle, contracted by its own inherent power; so, the arteries are
dilated by the stroke of the heart, but they contract or collapse of

  [49] Vide Chapter III. of the Disquisition on the Motion of the Heart
  and Blood.

You may also perform another experiment at the same time: if you fill
one of two basins of the same size with blood issuing per saltum from
an artery, the other with venous blood from a vein of the same animal,
you will have an opportunity of perceiving by the eye, both immediately
and by and by, when the blood in either vessel has become cold, what
differences there are between them. You will find that it is not as
they believe who fancy that there is one kind of blood in the arteries
and another in the veins, that in the arteries being of a more florid
colour, more frothy, and imbued with an abundance of I know not what
spirits, effervescing and swelling, and occupying a greater space, like
milk or honey set upon the fire. For were the blood which is thrown
from the left ventricle of the heart into the arteries, fermented into
any such frothy and flatulent fluid, so that a drop or two distended
the whole cavity of the aorta; unquestionably, upon the subsidence of
this fermentation, the blood would return to its original quantity of
a few drops; (and this, indeed, is the reason that some assign for the
usually empty state of the arteries in the dead body;) and so should it
be with the arterial blood in the cup, for so it is with boiling milk
and honey when they come to cool. But if in either basin you find blood
nearly of the same colour, not of very different consistency in the
coagulated state, forcing out serum in the same manner, and filling the
cups to the same height when cold that it did when hot, this will be
enough for any one to rest his faith upon, and afford argument enough,
I think, for rejecting the dreams that have been promulgated on the
subject. Sense and reason alike assure us that the blood contained in
the left ventricle is not of a different nature from that in the right.
And then, when we see that the mouth of the pulmonary artery is of the
same size as the aorta, and in other respects equal to that vessel, it
were imperative on us to affirm that the pulmonary artery was distended
by a single drop of spumous blood, as well as the aorta, and so that
the right as well as the left side of the heart was filled with a brisk
or fermenting blood.

The particulars which especially dispose men’s minds to admit diversity
in the arterial and venous blood are three in number: one, because in
arteriotomy the blood that flows is of a more florid hue than that
which escapes from a vein; a second, because in the dissection of dead
bodies the left ventricle of the heart, and the arteries in general,
are mostly found empty; a third, because the arterial blood is believed
to be more spirituous, and being replete with spirit is made to occupy
a much larger space. The causes and reasons, however, wherefore all
these things are so, present themselves to us when we ask after them.

1st. With reference to the colour it is to be observed, that wherever
the blood issues by a very small orifice, it is in some measure
strained, and the thinner and lighter part, which usually swims on
the top and is the most penetrating, is emitted. Thus, in phlebotomy,
when the blood escapes forcibly and to a distance, in a full stream,
and from a large orifice, it is thicker, has more body, and a darker
body; but, if it flows from a small orifice, and only drop by drop,
as it usually does when the bleeding fillet is untied, it is of a
brighter hue; for then it is strained as it were, and the thinner and
more penetrating portion only escapes; in the same way, in the bleeding
from the nose, in that which takes place from a leech-bite, or from
scarifications, or in any other way by diapedesis or transudation, the
blood is always seen to have a brighter cast, because the thickness
and firmness of the coats of the arteries render the outlet or outlets
smaller, and less disposed to yield a ready passage to the outpouring
blood; it happens also that when fat persons are let blood, the orifice
of the vein is apt to be compressed by the subcutaneous fat, by which
the blood is made to appear thinner, more florid, and in some sort
arterious. On the other hand, the blood that flows into a basin from a
large artery freely divided, will look venous. The blood in the lungs
is of a much more florid colour than it is in the arteries, and we know
how it is strained through the pulmonary tissue.

2d. The emptiness of the arteries in the dead body, which probably
misled Erasistratus in supposing that they only contained aereal
spirits, is caused by this, that when respiration ceases the lungs
collapse, and then the passages through them are closed; the heart,
however, continues for a time to contract upon the blood, whence we
find the left auricle more contracted, and the corresponding ventricle,
as well as the arteries at large, appearing empty, simply because there
is no supply of blood flowing round to fill them. In cases, however, in
which the heart has ceased to pulsate and the lungs to afford a passage
to the blood simultaneously, as in those who have died from drowning
or syncope, or who die suddenly, you will find the arteries, as well as
the veins, full of blood.

3d. With reference to the third point, or that of the spirits, it may
be said that, as it is still a question what they are, how extant in
the body, of what consistency, whether separate and distinct from the
blood and solids, or mingled with these,--upon each and all of these
points there are so many and such conflicting opinions, that it is
not wonderful that the spirits, whose nature is thus left so wholly
ambiguous, should serve as the common subterfuge of ignorance. Persons
of limited information, when they are at a loss to assign a cause
for anything, very commonly reply that it is done by the spirits;
and so they bring the spirits into play upon all occasions; even as
indifferent poets are always thrusting the gods upon the stage as a
means of unravelling the plot, and bringing about the catastrophe.

Fernelius, and many others, suppose that there are aereal spirits and
invisible substances. Fernelius proves that there are animal spirits,
by saying that the cells in the brain are apparently unoccupied, and
as nature abhors a vacuum, he concludes that in the living body they
are filled with spirits, just as Erasistratus had held that, because
the arteries were empty of blood, therefore they must be filled with
spirits. But Medical Schools admit three kinds of spirits: the natural
spirits flowing through the veins, the vital spirits through the
arteries, and the animal spirits through the nerves; whence physicians
say, out of Galen, that sometimes the parts of the brain are oppressed
by sympathy, because the faculty with the essence, i.e. the spirit, is
overwhelmed; and sometimes this happens independently of the essence.
Farther, besides the three orders of influxive spirits adverted to, a
like number of implanted or stationary spirits seem to be acknowledged;
but we have found none of all these spirits by dissection, neither
in the veins, nerves, arteries, nor other parts of living animals.
Some speak of corporeal, others of incorporeal spirits; and they who
advocate the corporeal spirits will have the blood, or the thinner
portion of the blood, to be the bond of union with the soul, the spirit
being contained in the blood as the flame is in the smoke of a lamp or
candle, and held admixed by the incessant motion of the fluid; others,
again, distinguish between the spirits and the blood. They who advocate
incorporeal spirits have no ground of experience to stand upon;
their spirits indeed are synonymous with powers or faculties, such
as a concoctive spirit, a chylopoietic spirit, a procreative spirit,
&c.--they admit as many spirits, in short, as there are faculties or

But then the schoolmen speak of a spirit of fortitude, prudence,
patience, and the other virtues, and also of a most holy spirit of
wisdom, and of every divine gift; and they besides suppose that there
are good and evil spirits that roam about or possess the body, that
assist or cast obstacles in the way. They hold some diseases to be
owing to a Cacodæmon or evil spirit, as there are others that are due
to a cacochemy or defective assimilation.

Although there is nothing more uncertain and questionable, then, than
the doctrine of spirits that is proposed to us, nevertheless physicians
seem for the major part to conclude, with Hippocrates, that our body is
composed or made up of three elements, viz. containing parts, contained
parts, and causes of action, spirits being understood by the latter
term. But if spirits are to be taken as synonymous with causes of
activity, whatever has power in the living body and a faculty of action
must be included under the denomination. It would appear, therefore,
that all spirits were neither aereal substances, nor powers, nor
habits; and that all were not incorporeal.

But keeping in view the points that especially interest us, others,
as leading to tediousness, being left unnoticed, it seems that the
spirits which flow by the veins or the arteries are not distinct
from the blood, any more than the flame of a lamp is distinct from
the inflammable vapour that is on fire; in short, that the blood and
these spirits signify one and the same thing, though different,--like
generous wine and its spirit; for as wine, when it has lost all its
spirit, is no longer wine, but a vapid liquor or vinegar; so blood
without spirit is not blood, but something else--clot or cruor; even
as a hand of stone, or of a dead body, is no hand in the most complete
sense, neither is blood void of the vital principle proper blood; it
is immediately to be held as corrupt when deprived of its spirit. The
spirit therefore which inheres in the arteries, and especially in the
blood which fills them, is to be regarded either as its act or agent,
in the same way as the spirit of wine in wine, and the spirit of aqua
vitæ in brandy, or as a flame kindled in alcohol, which lives and feeds
on, or is nourished by itself. The blood consequently, though richly
imbued with spirits, does not swell, nor ferment, nor rise to a head
through them, so as to require and occupy a larger space,--a fact that
may be ascertained beyond the possibility of question by the two cups
of equal size; it is to be regarded as wine, possessed of a large
amount of spirits, or, in the Hippocratic sense, of signal powers of
acting and effecting.

It is therefore the same blood in the arteries that is found in the
veins, although it may be admitted to be more spirituous, possessed
of higher vital force in the former than in the latter; but it is not
changed into anything more vaporous, or more aereal, as if there were
no spirits but such as are aereal, and no cause of action or activity
that is not of the nature of flatus or wind. But neither the animal,
natural, nor vital spirits which inhere in the solids, such as the
ligaments and nerves (especially if they be of so many different
species), and are contained within the viewless interstices of the
tissues, are to be regarded as so many different aereal forms, or kinds
of vapour.

And here I would gladly be informed by those who admit corporeal
spirits, but of a gaseous or vaporous consistency, in the bodies of
animals, whether or not they have the power of passing hither and
thither, like distinct bodies independently of the blood? Or whether
the spirits follow the blood in its motions, either as integral parts
of the fluid or as indissolubly connected with it, so that they can
neither quit the tissues nor pass hither nor thither without the influx
and reflux, and motion of the blood? For if the spirits exhaling from
the blood, like the vapour of water attenuated by heat, exist in a
state of constant flow and succession as the pabulum of the tissues, it
necessarily follows that they are not distinct from this pabulum, but
are incessantly disappearing; whereby it seems that they can neither
have influx nor reflux, nor passage, nor yet remain at rest without the
influx, the reflux, the passage [or stasis] of the blood, which is the
fluid that serves as their vehicle or pabulum.

And next I desire to know of those who tell us that the spirits are
formed in the heart, being compounded of the vapours or exhalations of
the blood (excited either by the heat of the heart or the concussion)
and the inspired air, whether such spirits are not to be accounted
much colder than the blood, seeing that both the elements of their
composition, namely, air and vapour, are much colder? For the vapour of
boiling water is much more bearable than the water itself; the flame of
a candle is less burning than the red-hot snuff, and burning charcoal
than incandescent iron or brass. Whence it would appear that spirits
of this nature rather receive their heat from the blood, than that
the blood is warmed by these spirits; such spirits are rather to be
regarded as fumes and excrementitious effluvia proceeding from the body
in the manner of odours, than in any way as natural artificers of the
tissues; a conclusion which we are the more disposed to admit, when we
see that they so speedily lose any virtue they may possess, and which
they had derived from the blood as their source,--they are at best of
a very frail and evanescent nature. Whence also it becomes probable
that the expiration of the lungs is a means by which these vapours
being cast off, the blood is fanned and purified; whilst inspiration is
a means by which the blood in its passage between the two ventricles
of the heart is tempered by the cold of the ambient atmosphere, lest,
getting heated, and blown up with a kind of fermentation, like milk or
honey set over the fire, it should so distend the lungs that the animal
got suffocated; somewhat in the same way, perchance, as one labouring
under a severe asthma, which Galen himself seems to refer to its
proper cause when he says it is owing to an obstruction of the smaller
arteries, viz. the vasa venosa et arteriosa. And I have found by
experience that patients affected with asthma might be brought out of
states of very imminent danger by having cupping-glasses applied, and
a plentiful and sudden affusion of cold water [upon the chest]. Thus
much--and perhaps it is more than was necessary--have I said on the
subject of spirits in this place, for I felt it proper to define them,
and to say something of their nature in a physiological disquisition.

I shall only further add, that they who descant on the calidum innatum
or innate heat, as an instrument of nature available for every purpose,
and who speak of the necessity of heat as the cherisher and retainer
in life of the several parts of the body, who at the same time
admit that this heat cannot exist unless connected with something,
and because they find no substance of anything like commensurate
mobility, or which might keep pace with the rapid influx and reflux
of this heat (in affections of the mind especially), take refuge in
spirits as most subtile substances, possessed of the most penetrating
qualities, and highest mobility--these persons see nothing less than
the wonderful and almost divine character of the natural operations
as proceeding from the instrumentality of this common agent, viz. the
calidum innatum; they farther regard these spirits as of a sublime,
lucid, ethereal, celestial, or divine nature, and the bond of the soul;
even as the vulgar and unlettered, when they do not comprehend the
causes of various effects, refer them to the immediate interposition
of the Deity. Whence they declare that the heat perpetually flowing
into the several parts is in virtue of the influx of spirits through
the channels of the arteries; as if the blood could neither move so
swiftly, nor penetrate so intimately, nor cherish so effectually. And
such faith do they put in this opinion, such lengths are they carried
by their belief, that they deny the contents of the arteries to be
blood! And then they proceed with trivial reasonings to maintain that
the arterial blood is of a peculiar kind, or that the arteries are
filled with such aereal spirits, and not with blood; all the while, in
opposition to everything which Galen has advanced against Erasistratus,
both on grounds of experiment and of reason. But that arterial blood
differs in nothing essential from venous blood has been already
sufficiently demonstrated; and our senses likewise assure us that the
blood and spirits do not flow in the arteries separately and disjoined,
but as one body.

We have occasion to observe so often as our hands, feet, or ears
have become stiff and cold, that as they recover again by the warmth
that flows into them, they acquire their natural colour and heat
simultaneously; that the veins which had become small and shrunk, swell
visibly and enlarge, so that when they regain their heat suddenly they
become painful; from which it appears, that that which by its influx
brings heat is the same which causes repletion and colour; now this can
be and is nothing but blood.

When an artery and a vein are divided, any one may clearly see that
the part of the vein towards the heart pours out no blood, whilst that
beyond the wound gives a torrent; the divided artery, on the contrary,
(as in my experiment on the carotids,) pours out a flood of pure blood
from the orifice next the heart, and in jets as if it were forced
from a syringe, whilst from the further orifice of the divided artery
little or no blood escapes. This experiment therefore plainly proves
in what direction the current sets in either order of vessels--towards
the heart in the veins, from the heart in the arteries; it also shows
with what velocity the current moves, not gradually and by drops, but
even with violence. And lest any one, by way of subterfuge, should
take shelter in the notion of invisible spirits, let the orifice of
the divided vessel be plunged under water or oil, when, if there be
any air contained in it, the fact will be proclaimed by a succession
of visible bubbles. Hornets, wasps, and other insects of the same
description plunged in oil, and so suffocated, emit bubbles of air from
their tail whilst they are dying; whence it is not improbable that they
thus respire when alive; for all animals submerged and drowned, when
they finally sink to the bottom and die, emit bubbles of air from the
mouth and lungs. It is also demonstrated by the same experiment, that
the valves of the veins act with such accuracy, that air blown into
them does not penetrate; much less then can blood make its way through
them:--it is certain, I say, that neither sensibly nor insensibly, nor
gradually and drop by drop, can any blood pass from the heart by the

And that no one may seek shelter in asserting that these things are
so when nature is disturbed and opposed, but not when she is left to
herself and at liberty to act; that the same things do not come to pass
in morbid and unusual states as in the healthy and natural condition;
they are to be met by saying, that if it were so, if it happened
that so much blood was lost from the farther orifice of a divided
vein because nature was disturbed, still that the incision does not
close the nearer orifice, from which nothing either escapes or can be
expressed, whether nature be disturbed or not. Others argue in the
same way, maintaining that, although the blood immediately spurts out
in such profusion with every beat, when an artery is divided near the
heart, it does not therefore follow that the blood is propelled by
the pulse when the heart and artery are entire. It is most probable,
however, that every stroke impels something; and that there would be
no pulse of the container, without an impulse being communicated to
the thing contained, seems certain. Yet some, that they may seize upon
a farther means of defence, and escape the necessity of admitting the
circulation, do not fear to affirm that the arteries in the living
body and in the natural state are already so full of blood, that they
are incapable of receiving another drop; and so also of the ventricles
of the heart. But it is indubitable that, whatever the degree of
distension and the extent of contraction of the heart and arteries,
they are still in a condition to receive an additional quantity of
blood forced into them, and that this is far more than is usually
reckoned in grains or drops, seems also certain. For if the ventricles
become so excessively distended that they will admit no more blood,
the heart ceases to beat, (and we have occasional opportunities of
observing the fact in our vivisections,) and, continuing tense and
resisting, death by asphyxia ensues.

In the work on the Motion of the Heart and Blood, I have already
sufficiently discussed the question as to whether the blood in its
motion was attracted, or impelled, or moved by its own inherent nature.
I have there also spoken at length of the action and office, of the
dilatation and contraction of the heart, and have shown what these
truly are, and how the heart contracts during the diastole of the
arteries; so that I must hold those who take points for dispute from
among them as either not understanding the subject, or as unwilling to
look at things for themselves, and to investigate them with their own

  [50] Vide Chapter XIV.

For my part, I believe that no other kind of attraction can be
demonstrated in the living body save that of the nutriment, which
gradually and incessantly passes on to supply the waste that takes
place in the tissues; in the same way as the oil rises in the wick of
a lamp to be consumed by the flame. Whence I conclude that the primary
and common organ of all sensible attraction and impulsion is of the
nature of sinew (nervus), or fibre, or muscle, and this to the end that
it may be contractile, that contracting it may be shortened, and so
either stretch out, draw towards, or propel. But these topics will be
better discussed elsewhere, when we speak of the organs of motion in
the animal body.

To those who repudiate the circulation because they neither see
the efficient nor final cause of it, and who exclaim, cui bono? I
have yet to reply, having hitherto taken no note of the ground of
objection which they take up. And first I own I am of opinion that our
first duty is to inquire whether the thing be or not, before asking
wherefore it is? for from the facts and circumstances which meet us
in the circulation admitted, established, the ends and objects of its
institution are especially to be sought. Meantime I would only ask,
how many things we admit in physiology, pathology, and therapeutics,
the causes of which are unknown to us? That there are many, no one
doubts--the causes of putrid fevers, of revulsions, of the purgation of
excrementitious matters, among the number.

Whoever, therefore, sets himself in opposition to the circulation,
because, if it be acknowledged, he cannot account for a variety
of medical problems, nor in the treatment of diseases and the
administration of medicines, give satisfactory reasons for the
phenomena that appear; or who will not see that the precepts he has
received from his teachers are false; or who thinks it unseemly to give
up accredited opinions; or who regards it as in some sort criminal
to call in question doctrines that have descended through a long
succession of ages, and carry the authority of the ancients;--to all
of these I reply: that the facts cognizable by the senses wait upon no
opinions, and that the works of nature bow to no antiquity; for indeed
there is nothing either more ancient or of higher authority than nature.

To those who object to the circulation as throwing obstacles in the
way of their explanations of the phenomena that occur in medical
cases (and there are persons who will not be content to take up with
a new system, unless it explains everything, as in astronomy), and
who oppose it with their own erroneous assumptions, such as that,
if it be true, phlebotomy cannot cause revulsion, seeing that the
blood will still continue to be forced into the affected part; that
the passage of excrementitious matters and foul humours through the
heart, that most noble and principal viscus, is to be apprehended;
that an efflux and excretion, occasionally of foul and corrupt blood,
takes place from the same body, from different parts, even from the
same part and at the same time, which, were the blood agitated by a
continuous current, would be shaken and effectually mixed in passing
through the heart, and many points of the like kind admitted in our
medical schools, which are seen to be repugnant to the doctrine of
the circulation,--to them I shall not answer farther here, than that
the circulation is not always the same in every place, and at every
time, but is contingent upon many circumstances: the more rapid or
slower motion of the blood, the strength or weakness of the heart as
the propelling organ, the quantity and quality or constitution of the
blood, the rigidity or laxity of the tissues, and the like. A thicker
blood, of course, moves more slowly through narrower channels; it is
more effectually strained in its passage through the substance of the
liver than through that of the lungs. It has not the same velocity
through flesh and the softer parenchymatous structures and through
sinewy parts of greater compactness and consistency: for the thinner
and purer and more spirituous part permeates more quickly, the thicker
more earthy and indifferently concocted portion moves more slowly, or
is refused admission. The nutritive portion, or ultimate aliment of the
tissues, the dew or cambium, is of a more penetrating nature, inasmuch
as it has to be added everywhere, and to everything that grows and is
nourished in its length and thickness, even to the horns, nails, hair,
and feathers; and then the excrementitious matters have to be secreted
in some places, where they accumulate, and either prove a burthen or
are concocted. But I do not imagine that the excrementitious fluids
or bad humours when once separated, nor the milk, the phlegm, and the
spermatic fluid, nor the ultimate nutritive part, the dew or cambium,
necessarily circulate with the blood: that which nourishes every part
adheres and becomes agglutinated to it. Upon each of these topics and
various others besides, to be discussed and demonstrated in their
several places, viz. in the physiology and other parts of the art of
medicine, as well as of the consequences, advantages or disadvantages
of the circulation of the blood, I do not mean to touch here; it were
fruitless indeed to do so until the circulation has been established
and conceded as a fact. And here the example of astronomy is by no
means to be followed, in which from mere appearances or phenomena that
which is in fact, and the reason wherefore it is so, are investigated.
But as he who inquires into the cause of an eclipse must be placed
beyond the moon if he would ascertain it by sense, and not by reason,
still in reference to things sensible, things that come under the
cognizance of the senses, no more certain demonstration or means of
gaining faith can be adduced than examination by the senses, than
ocular inspection.

There is one remarkable experiment which I would have every one try
who is anxious for truth, and by which it is clearly shown that the
arterial pulse is owing to the impulse of the blood. Let a portion
of the dried intestine of a dog or wolf, or any other animal, such
as we see hung up in the druggists’ shops, be taken and filled with
water, and then secured at both ends like a sausage: by tapping with
the finger at one extremity, you will immediately feel a pulse and
vibration in any other part to which you apply the fingers, as you do
when you feel the pulse at the wrist. In this way, indeed, and also by
means of a distended vein, you may accurately, either in the dead or
living body, imitate and show every variety of the pulse, whether as to
force, frequency, volume, rhythm, &c. Just as in a long bladder full of
fluid, or in an oblong drum, every stroke upon one end is immediately
felt at the other; so also in a dropsy of the belly and in abscesses
under the skin, we are accustomed to distinguish between collections
of fluid and of air, between anasarca and tympanites in particular.
If a slap or push given on one side is clearly felt by a hand placed
on the other side, we judge the case to be tympanites [?]; not, as
falsely asserted, because we hear a sound like that of a drum, and this
produced by flatus, which never happens [?]; but because, as in a drum,
every the slightest tap passes through and produces a certain vibration
on the opposite side; for it indicates that there is a serous and
ichorous substance present, of such a consistency as urine, and not any
sluggish or viscid matter as in anasarca, which when struck retains the
impress of the blow or pressure, and does not transmit the impulse.

Having brought forward this experiment I may observe, that a most
formidable objection to the circulation of the blood rises out of it,
which, however, has neither been observed nor adduced by any one who
has written against me. When we see by the experiment just described,
that the systole and diastole of the pulse can be accurately imitated
without any escape of fluid, it is obvious that the same thing may
take place in the arteries from the stroke of the heart, without the
necessity for a circulation, but like Euripus, with a mere motion of
the blood alternately backwards and forwards. But we have already
satisfactorily replied to this difficulty; and now we venture to say
that the thing could not be so in the arteries of a living animal;
to be assured of this it is enough to see that the right auricle is
incessantly injecting the right ventricle of the heart with blood, the
return of which is effectually prevented by the tricuspid valves; the
left auricle in like manner filling the left ventricle, the return
of the blood there being opposed by the mitral valves; and then the
ventricles in their turn are propelling the blood into either great
artery, the reflux in each being prevented by the sigmoid valves in
its orifice. Either, consequently, the blood must move on incessantly
through the lungs, and in like manner within the arteries of the body,
or stagnating and pent up, it must rupture the containing vessels,
or choke the heart by over distension, as I have shown it to do in
the vivisection of a snake, described in my book on the Motion of the
Blood. To resolve this doubt I shall relate two experiments among many
others, the first of which, indeed, I have already adduced, and which
show with singular clearness that the blood flows incessantly and with
great force and in ample abundance in the veins towards the heart. The
internal jugular vein of a live fallow deer having been exposed, (many
of the nobility and his most serene majesty the king, my master, being
present,) was divided; but a few drops of blood were observed to escape
from the lower orifice rising up from under the clavicle; whilst from
the superior orifice of the vein and coming down from the head, a
round torrent of blood gushed forth. You may observe the same fact any
day in practising phlebotomy: if with a finger you compress the vein a
little below the orifice, the flow of blood is immediately arrested;
but the pressure being removed, forthwith the flow returns as before.

From any long vein of the forearm get rid of the blood as much as
possible by holding the hand aloft and pressing the blood towards the
trunk, you will perceive the vein collapsed and leaving, as it were,
in a furrow of the skin; but now compress the vein with the point of
a finger, and you will immediately perceive all that part of it which
is towards the hand, to enlarge and to become distended with the blood
that is coming from the hand. How comes it when the breath is held and
the lungs thereby compressed, a large quantity of air having been taken
in, that the vessels of the chest are at the same time obstructed, the
blood driven into the face, and the eyes rendered red and suffused?
Why is it, as Aristotle asks in his problems, that all the actions
are more energetically performed when the breath is held than when
it is given? In like manner, when the frontal and lingual veins are
incised, the blood is made to flow more freely by compressing the neck
and holding the breath. I have several times opened the breast and
pericardium of a man within two hours after his execution by hanging,
and before the colour had totally left the face, and in presence of
many witnesses, have demonstrated the right auricle of the heart and
lungs distended with blood; the auricle in particular of the size
of a large man’s fist, and so full of blood that it looked as if it
would burst. This great distension, however, had disappeared next day,
the body having stiffened and become cold, and the blood having made
its escape through various channels. These and other similar facts,
therefore, make it sufficiently certain that the blood flows through
the whole of the veins of the body towards the base of the heart, and
that unless there was a further passage afforded it, it would be pent
up in these channels, or would oppress and overwhelm the heart; as on
the other hand, did it not flow outwards by the arteries, but was found
regurgitating, it would soon be seen how much it would oppress.

I add another observation. A noble knight, Sir Robert Darcy, an
ancestor of that celebrated physician and most learned man, my very
dear friend Dr. Argent, when he had reached to about the middle period
of life, made frequent complaint of a certain distressing pain in
the chest, especially in the night season; so that dreading at one
time syncope, at another suffocation in his attacks he led an unquiet
and anxious life. He tried many remedies in vain, having had the
advice of almost every medical man. The disease going on from bad
to worse, he by and by became cachectic and dropsical, and finally,
grievously distressed, he died in one of his paroxysms. In the body
of this gentleman, at the inspection of which there were present Dr.
Argent, then president of the College of Physicians, and Dr. Gorge, a
distinguished theologian and preacher, who was pastor of the parish,
we found the wall of the left ventricle of the heart ruptured, having
a rent in it of size sufficient to admit any of my fingers, although
the wall itself appeared sufficiently thick and strong; this laceration
had apparently been caused by an impediment to the passage of the blood
from the left ventricle into the arteries.

I was acquainted with another strong man, who having received an
injury and affront from one more powerful than himself, and upon whom
he could not have his revenge, was so overcome with hatred and spite
and passion, which he yet communicated to no one, that at last he
fell into a strange distemper, suffering from extreme oppression and
pain of the heart and breast, and the prescriptions of none of the
very best physicians proving of any avail, he fell in the course of
a few years into a scorbutic and cachectic state, became tabid and
died. This patient only received some little relief when the whole of
his chest was pummelled or kneaded by a strong man, as a baker kneads
dough. His friends thought him poisoned by some maleficent influence,
or possessed with an evil spirit. His jugular arteries, enlarged to the
size of the thumb, looked like the aorta itself, or they were as large
as the descending aorta; they had pulsated violently, and appeared
like two long aneurisms. These symptoms had led to trying the effects
of arteriotomy in the temples, but with no relief. In the dead body I
found the heart and aorta so much gorged and distended with blood, that
the cavities of the ventricles equalled those of a bullock’s heart in
size. Such is the force of the blood pent up, and such are the effects
of its impulse.

We may therefore conclude, that although there may be impulse without
any exit, as illustrated in the experiment lately spoken of, still
that this could not take place in the vessels of living creatures
without most serious dangers and impediments. From this, however, it
is manifest that the blood in its course does not everywhere pass with
the same celerity, neither with the same force in all places and at all
times, but that it varies greatly according to age, sex, temperament,
habit of body, and other contingent circumstances, external as well
as internal, natural or non-natural. For it does not course through
intricate and obstructed passages with the same readiness that it does
through straight, unimpeded, and pervious channels. Neither does it
run through close, hard, and crowded parts, with the same velocity
as through spongy, soft, and permeable tissues. Neither does it flow
and penetrate with such swiftness when the impulse [of the heart] is
slow and weak, as when this is forcible and frequent, in which case
the blood is driven onwards with vigour and in large quantity. Nor
is the same blood, when it has become more consistent or earthy, so
penetrative as when it is more serous and attenuated or liquid. And
then it seems only reasonable to think that the blood in its circuit
passes more slowly through the kidneys than through the substance of
the heart; more swiftly through the liver than through the kidneys;
through the spleen more quickly than through the lungs, and through
the lungs more speedily than through any of the other viscera or the
muscles, in proportion always to the denseness or sponginess of the
tissue of each.

We may be permitted to take the same view of the influence of age, sex,
temperament, and habit of body, whether this be hard or soft; of that
of the ambient cold which condenses bodies, and makes the veins in the
extremities to shrink and almost to disappear, and deprives the surface
both of colour and heat; and also that of meat and drink which render
the blood more watery, by supplying fresh nutritive matter. From the
veins, therefore, the blood flows more freely in phlebotomy when the
body is warm than when it is cold. We also observe the signal influence
of the affections of the mind when a timid person is bled and happens
to faint: immediately the flow of blood is arrested, a deadly pallor
overspreads the surface, the limbs stiffen, the ears sing, the eyes are
dazzled or blinded, and, as it were, convulsed. But here I come upon
a field where I might roam freely and give myself up to speculation.
And, indeed, such a flood of light and truth breaks in upon me here;
occasion offers of explaining so many problems, of resolving so many
doubts, of discovering the causes of so many slighter and more serious
diseases, and of suggesting remedies for their cure, that the subject
seems almost to demand a separate treatise. And it will be my business
in my “Medical Observations,” to lay before my reader matter upon all
these topics which shall be worthy of the gravest consideration.

And what indeed is more deserving of attention than the fact that in
almost every affection, appetite, hope, or fear, our body suffers,
the countenance changes, and the blood appears to course hither and
thither. In anger the eyes are fiery and the pupils contracted; in
modesty the cheeks are suffused with blushes; in fear, and under a
sense of infamy and of shame, the face is pale, but the ears burn as
if for the evil they heard or were to hear; in lust how quickly is the
member distended with blood and erected! But, above all, and this is
of the highest interest to the medical practitioner,--how speedily is
pain relieved or removed by the detraction of blood, the application
of cupping-glasses, or the compression of the artery which leads to a
part? It sometimes vanishes as if by magic. But these are topics that
I must refer to my “Medical Observations,” where they will be found
exposed at length and explained.

Some weak and inexperienced persons vainly seek by dialectics and
far-fetched arguments, either to upset or establish things that are
only to be founded on anatomical demonstration, and believed on the
evidence of the senses. He who truly desires to be informed of the
question in hand, and whether the facts alleged be sensible, visible,
or not, must be held bound either to look for himself, or to take
on trust the conclusions to which they have come who have looked;
and indeed there is no higher method of attaining to assurance and
certainty. Who would pretend to persuade those who had never tasted
wine that it was a drink much pleasanter to the palate than water? By
what reasoning should we give the blind from birth to know that the sun
was luminous, and far surpassed the stars in brightness? And so it is
with the circulation of the blood, which the world has now had before
it for so many years, illustrated by proofs cognizable by the senses,
and confirmed by various experiments. No one has yet been found to
dispute the sensible facts, the motion, efflux and afflux of the blood,
by like observations based on the evidence of sense, or to oppose
the experiments adduced, by other experiments of the same character;
nay, no one has yet attempted an opposition on the ground of ocular

There have not been wanting many who, inexperienced and ignorant of
anatomy, and making no appeal to the senses in their opposition, have,
on the contrary, met it with empty assertions, and mere suppositions,
with assertions derived from the lessons of teachers and captious
cavillings; many, too, have vainly sought refuge in words, and these
not always very nicely chosen, but reproachful and contumelious; which,
however, have no farther effect than to expose their utterer’s vanity
and weakness, and ill breeding and lack of the arguments that are to
be sought in the conclusions of the senses, and false sophistical
reasonings that seem utterly opposed to sense. Even as the waves of
the Sicilian sea, excited by the blast, dash against the rocks around
Charybdis, and then hiss and foam, and are tossed hither and thither;
so do they who reason against the evidence of their senses.

Were nothing to be acknowledged by the senses without evidence
derived from reason, or occasionally even contrary to the previously
received conclusions of reason, there would now be no problem left
for discussion. Had we not our most perfect assurances by the senses,
and were not their perceptions confirmed by reasoning, in the same
way as geometricians proceed with their figures, we should admit no
science of any kind; for it is the business of geometry, from things
sensible, to make rational demonstration of things that are not
sensible; to render credible or certain things abstruse and beyond
sense from things more manifest and better known. Aristotle counsels
us better when, in treating of the generation of bees, he says:[51]
“Faith is to be given to reason, if the matters demonstrated agree
with those that are perceived by the senses; when the things have been
thoroughly scrutinized, then are the senses to be trusted rather than
the reason.” Whence it is our duty to approve or disapprove, to receive
or reject everything only after the most careful examination; but to
examine, to test whether anything have been well or ill advanced, to
ascertain whether some falsehood does not lurk under a proposition, it
is imperative on us to bring it to the proof of sense, and to admit or
reject it on the decision of sense. Whence Plato in his Critias says,
that the explanation of those things is not difficult of which we can
have experience; whilst they are not of apt scientific apprehension who
have no experience.

  [51] De Generat. Animal. lib. iii, cap. x.

How difficult is it to teach those who have no experience, the things
of which they have not any knowledge by their senses! And how useless
and intractable, and unimpregnable to true science are such auditors!
They show the judgment of the blind in regard to colours, of the deaf
in reference to concords. Who ever pretended to teach the ebb and flow
of the tide, or from a diagram to demonstrate the measurements of the
angles and the proportions of the sides of a triangle to a blind man,
or to one who had never seen the sea nor a diagram? He who is not
conversant with anatomy, inasmuch as he forms no conception of the
subject from the evidence of his own eyes, is virtually blind to all
that concerns anatomy, and unfit to appreciate what is founded thereon;
he knows nothing of that which occupies the attention of the anatomist,
nor of the principles inherent in the nature of the things which guide
him in his reasonings; facts and inferences as well as their sources
are alike unknown to such a one. But no kind of science can possibly
flow, save from some pre-existing knowledge of more obvious things;
and this is one main reason why our science in regard to the nature
of celestial bodies, is so uncertain and conjectural. I would ask of
those who profess a knowledge of the causes of all things, why the
two eyes keep constantly moving together, up or down, to this side or
to that, and not independently, one looking this way, another that;
why the two auricles of the heart contract simultaneously, and the
like? Are fevers, pestilence, and the wonderful properties of various
medicines to be denied because their causes are unknown? Who can tell
us why the fœtus in utero, breathing no air up to the tenth month of
its existence, is yet not suffocated? Born in the course of the seventh
or eighth month, and having once breathed, it is nevertheless speedily
suffocated if its respiration be interrupted. Why can the fœtus still
contained within the uterus, or enveloped in the membranes, live
without respiration; whilst once exposed to the air, unless it breathes
it inevitably dies?[52]

  [52] Vide Chapter VI. of the Disq. on the Motion of the Heart and

Observing that many hesitate to acknowledge the circulation, and others
oppose it, because, as I conceive, they have not rightly understood
me, I shall here recapitulate briefly what I have said in my work on
the Motion of the Heart and Blood. The blood contained in the veins,
in its magazine, and where it is collected in largest quantity, viz.
in the vena cava, close to the base of the heart and right auricle,
gradually increasing in temperature by its internal heat, and becoming
attenuated, swells and rises like bodies in a state of fermentation,
whereby the auricle being dilated, and then contracting, in virtue
of its pulsative power, forthwith delivers its charge into the right
ventricle; which being filled, and the systole ensuing, the charge,
hindered from returning into the auricle by the tricuspid valves, is
forced into the pulmonary artery, which stands open to receive it,
and is immediately distended with it. Once in the pulmonary artery,
the blood cannot return, by reason of the sigmoid valves; and then
the lungs, alternately expanded and contracted during inspiration and
expiration, afford it passage by the proper vessels into the pulmonary
veins; from the pulmonary veins, the left auricle, acting equally and
synchronously with the right auricle, delivers the blood into the left
ventricle; which acting harmoniously with the right ventricle, and all
regress being prevented by the mitral valves, the blood is projected
into the aorta, and consequently impelled into all the arteries of
the body. The arteries, filled by this sudden push, as they cannot
discharge themselves so speedily, are distended; they receive a shock,
or undergo their diastole. But as this process goes on incessantly, I
infer that the arteries both of the lungs and of the body at large,
under the influence of such a multitude of strokes of the heart and
injections of blood, would finally become so over-gorged and distended,
that either any further injection must cease, or the vessels would
burst, or the whole blood in the body would accumulate within them,
were there not an exit provided for it.

The same reasoning is applicable to the ventricles of the heart:
distended by the ceaseless action of the auricles, did they not
disburthen themselves by the channels of the arteries, they would by
and by become over-gorged, and be fixed and made incapable of all
motion. Now this, my conclusion, is true and necessary, if my premises
be true; but that these are either true or false, our senses must
inform us, not our reason--ocular inspection, not any process of the

I maintain further, that the blood in the veins always and everywhere
flows from less to greater branches, and from every part towards
the heart; whence I gather that the whole charge which the arteries
receive, and which is incessantly thrown into them, is delivered to the
veins, and flows back by them to the source whence it came. In this
way, indeed, is the circulation of the blood established: by an efflux
and reflux from and to the heart; the fluid being forcibly projected
into the arterial system, and then absorbed and imbibed from every
part by the veins, it returns through these in a continuous stream.
That all this is so, sense assures us; and necessary inference from the
perceptions of sense takes away all occasion for doubt. Lastly, this is
what I have striven, by my observations and experiments, to illustrate
and make known; I have not endeavoured from causes and probable
principles to demonstrate my propositions, but, as of higher authority,
to establish them by appeals to sense and experiment, after the manner
of anatomists.

And here I would refer to the amount of force, even of violence, which
sight and touch make us aware of in the heart and greater arteries;
and to the systole and diastole constituting the pulse in the large
warm-blooded animals, which I do not say is equal in all the vessels
containing blood, nor in all animals that have blood; but which is of
such a nature and amount in all, that a flow and rapid passage of the
blood through the smaller arteries, the interstices of the tissues, and
the branches of the veins, must of necessity take place; and therefore
there is a circulation.

For neither do the most minute arteries, nor the veins, pulsate; but
the larger arteries and those near the heart pulsate, because they
do not transmit the blood so quickly as they receive it.[53] Having
exposed an artery, and divided it so that the blood shall flow out as
fast and freely as it is received, you will scarcely perceive any pulse
in that vessel; and for the simple reason, that an open passage being
afforded, the blood escapes, merely passing through the vessel, not
distending it. In fishes, serpents, and the colder animals, the heart
beats so slowly and feebly, that a pulse can scarcely be perceived in
the arteries; the blood in them is transmitted gradually. Whence in
them, as also in the smaller branches of the arteries in man, there is
no distinction between the coats of the arteries and veins, because
the arteries have to sustain no shock from the impulse of the blood.

  [53] Vide Chapter III, on the Motion of the Heart and Blood.

An artery denuded and divided in the way I have indicated, sustains no
shock, and therefore does not pulsate; whence it clearly appears that
the arteries have no inherent pulsative power, and that neither do
they derive any from the heart; but that they undergo their diastole
solely from the impulse of the blood; for in the full stream, flowing
to a distance, you may see the systole and diastole, all the motions
of the heart--their order, force, rhythm, &c.,[54] as it were in a
mirror, and even perceive them by the touch. Precisely as in the water
that is forced aloft, through a leaden pipe, by working the piston
of a forcing-pump, each stroke of which, though the jet be many feet
distant, is nevertheless distinctly perceptible,--the beginning,
increasing strength, and end of the impulse, as well as its amount,
and the regularity or irregularity with which it is given, being
indicated, the same precisely is the case from the orifice of a divided
artery; whence, as in the instance of the forcing engine quoted, you
will perceive that the efflux is uninterrupted, although the jet is
alternately greater and less. In the arteries, therefore, besides the
concussion or impulse of the blood, the pulse or beat of the artery,
which is not equally exhibited in all, there is a perpetual flow and
motion of the blood, which returns in an unbroken stream to the point
from whence it commenced--the right auricle of the heart.

  [54] Vide Chapter III, on the Motion of the Heart and Blood.

All these points you may satisfy yourself upon, by exposing one of the
longer arteries, and having taken it between your finger and thumb,
dividing it on the side remote from the heart. By the greater or less
pressure of your fingers, you can have the vessel pulsating less or
more, or losing the pulse entirely, and recovering it at will. And
as these things proceed thus when the chest is uninjured, so also do
they go on for a short time when the thorax is laid open, and the
lungs having collapsed, all the respiratory motions have ceased; here,
nevertheless, for a little while you may perceive the left auricle
contracting and emptying itself, and becoming whiter; but by and by
growing weaker and weaker, it begins to intermit, as does the left
ventricle also, and then it ceases to beat altogether, and becomes
quiescent. Along with this, and in the same measure, does the stream
of blood from the divided artery grow less and less, the pulse of the
vessel weaker and weaker, until at last, the supply of blood and the
impulse of the left ventricle failing, nothing escapes from it. You
may perform the same experiment, tying the pulmonary veins, and so
taking away the pulse of the left auricle, or relaxing the ligature,
and restoring it at pleasure. In this experiment, too, you will observe
what happens in moribund animals--viz. that the left ventricle first
ceases from pulsation and motion, then the left auricle, next the right
ventricle, finally the right auricle; so that where the vital force and
pulse first begin, there do they also last fail.

All of these particulars having been recognized by the senses, it is
manifest that the blood passes through the lungs, not through the
septum [in its course from the right to the left side of the heart],
and only through them when they are moved in the act of respiration,
not when they are collapsed and quiescent; whence we see the probable
reason wherefore nature has instituted the foramen ovale in the fœtus,
instead of sending the blood by the way of the pulmonary artery into
the left auricle and ventricle, which foramen she closes when the
new-born creature begins to breathe freely. We can also now understand
why, when the vessels of the lungs become congested and oppressed,
and in those who are affected with serious diseases, it should be
so dangerous and fatal a symptom when the respiratory organs become

We perceive further, why the blood is so florid in the lungs, which
is, because it is thinner, as having there to undergo filtration.

Still further; from the summary which precedes, and by way of
satisfying those who are importunate in regard to the causes of the
circulation, and incline to regard the power of the heart as competent
to everything--as that it is not only the seat and source of the
pulse which propels the blood, but also, as Aristotle thinks, of the
power which attracts and produces it; moreover, that the spirits are
engendered by the heart, and the influxive vital heat, in virtue of
the innate heat of the heart, as the immediate instrument of the
soul, or common bond and prime organ in the performance of every act
of vitality; in a word, that the motion, perfection, heat, and every
property besides of the blood and spirits are derived from the heart,
as their fountain or original, (a doctrine as old as Aristotle, who
maintained all these qualities to inhere in the blood, as heat inheres
in boiling water or pottage,) and that the heart is the primary cause
of pulsation and life; to those persons, did I speak openly, I should
say that I do not agree with the common opinion; there are numerous
particulars to be noted in the production of the parts of the body
which incline me this way, but which it does not seem expedient to
enter upon here. Before long, perhaps, I shall have occasion to lay
before the world things that are more wonderful than these, and that
are calculated to throw still greater light upon natural philosophy.

Meantime I shall only say, and, without pretending to demonstrate it,
propound--with the good leave of our learned men, and with all respect
for antiquity--that the heart, with the veins and arteries and the
blood they contain, is to be regarded as the beginning and author,
and fountain and original of all things in the body, the primary
cause of life; and this in the same acceptation as the brain with its
nerves, organs of sense and spinal marrow inclusive, is spoken of as
the one and general organ of sensation. But if by the word heart the
mere body of the heart, made up of its auricles and ventricles, be
understood, then I do not believe that the heart is the fashioner of
the blood; neither do I imagine that the blood has powers, properties,
motion, or heat, as the gift of the heart; lastly, neither do I admit
that the cause of the systole and contraction is the same as that of
the diastole or dilatation, whether in the arteries, auricles, or
ventricles; for I hold that that part of the pulse which is designated
the diastole depends on another cause different from the systole, and
that it must always and everywhere precede any systole; I hold that
the innate heat is the first cause of dilatation, and that the primary
dilatation is in the blood itself, after the manner of bodies in a
state of fermentation, gradually attenuated and swelling, and that in
the blood is this finally extinguished; I assent to Aristotle’s example
of gruel or milk upon the fire, to this extent, that the rising and
falling of the blood does not depend upon vapours or exhalations, or
spirits, or anything rising in a vaporous or aëreal shape, nor upon any
external agency, but upon an internal principle under the control of

Nor is the heart, as some imagine, anything like a chauffer or fire, or
heated kettle, and so the source of the heat of the blood; the blood,
instead of receiving, rather gives heat to the heart, as it does to
all the other parts of the body; for the blood is the hottest element
in the body; and it is on this account that the heart is furnished
with coronary arteries and veins; it is for the same reason that other
parts have vessels, viz. to secure the access of warmth for their
due conservation and stimulation; so that the warmer any part is,
the greater is its supply of blood, or otherwise; where the blood is
in largest quantity, there also is the heat highest. For this reason
is the heart, remarkable through its cavities, to be viewed as the
elaboratory, fountain, and perennial focus of heat, and as comparable
to a hot kettle, not because of its proper substance, but because of
its contained blood; for the same reason, because they have numerous
veins or vessels containing blood, are the liver, spleen, lungs, &c.,
reputed hot parts. And in this way do I view the native or innate heat
as the common instrument of every function, the prime cause of the
pulse among the rest. This, however, I do not mean to state absolutely,
but only propose it by way of thesis. Whatever may be objected to it by
good and learned men, without abusive or contemptuous language, I shall
be ready to listen to--I shall even be most grateful to any one who
will take up and discuss the subject.

These, then, are, as it were, the very elements and indications of
the passage and circulation of the blood, viz. from the right auricle
into the right ventricle; from the right ventricle by the way of the
lungs into the left auricle; thence into the left ventricle and aorta;
whence by the arteries at large through the pores or interstices of the
tissues into the veins, and by the veins back again with great rapidity
to the base of the heart.

There is an experiment on the veins by which any one that chooses may
convince himself of this truth: Let the arm be bound with a moderately
tight bandage, and then, by opening and shutting the hand, make all
the veins to swell as much as possible, and the integuments below the
fillets to become red; and now let the arm and hand be plunged into
very cold water, or snow, until the blood pent up in the veins shall
have become cooled down; then let the fillet be undone suddenly, and
you will perceive, by the cold blood returning to the heart, with what
celerity the current flows, and what an effect it produces when it
has reached the heart; so that you will no longer be surprised that
some should faint when the fillet is undone after venesection.[55]
This experiment shows that the veins swell below the ligature not with
attenuated blood, or with blood raised by spirits or vapours, for
the immersion in the cold water would repress their ebullition, but
with blood only, and such as could never make its way back into the
arteries, either by open-mouthed communications or by devious passages;
it shows, moreover, how and in what way those who are travelling over
snowy mountains are sometimes stricken suddenly with death, and other
things of the same kind.

  [55] Vide Chapter XI, of the Motion of the Heart, &c.

Lest it should seem difficult for the blood to make its way through
the pores of the various structures of the body, I shall add one
illustration: The same thing happens in the bodies of those that are
hanged or strangled, as in the arm that is bound with a fillet: all
the parts beyond the noose,--the face, lips, tongue, eyes, and every
part of the head appear gorged with blood, swollen, and of a deep red
or livid colour; but if the noose be relaxed, in whatever position you
have the body, before many hours have passed you will perceive the
whole of the blood to have quitted the head and face, and gravitated
through the pores of the skin, flesh, and other structures, from the
superior parts towards those that are inferior and dependent, until
they become tumid and of a dark colour. But if this happens in the dead
body, with the blood dead and coagulated, the frame stiffened with
the chill of death, the passages all compressed or blocked up, it is
easy to perceive how much more apt it will be to occur in the living
subject, when the blood is alive and replete with spirits, when the
pores are all open, the fluid ready to penetrate, and the passage in
every way made easy.

When the ingenious and acute Descartes, (whose honourable mention of
my name demands my acknowledgments,) and others, having taken out the
heart of a fish, and put it on a plate before them, see it continuing
to pulsate (in contracting), and when it raises or erects itself and
becomes firm to the touch, they think it enlarges, expands, and that
its ventricles thence become more capacious. But, in my opinion, they
do not observe correctly; for, at the time the heart gathers itself
up, and becomes erect, it is certain that it is rather lessened in
every one of its dimensions; that it is in its systole, in short,
not in its diastole. Neither, on the contrary, when it collapses
and sinks down, is it then properly in its state of diastole and
distension, by which the ventricles become more capacious. But as we
do not say that the heart is in the state of diastole in the dead
body, as having sunk relaxed after the systole, but is then collapsed,
and without all motion--in short is in a state of rest, and not
distended. It is only truly distended, and in the proper state of
diastole, when it is filled by the charge of blood projected into it
by the contraction of the auricles; a fact which sufficiently appears
in the course of vivisections. Descartes therefore does not perceive
how much the relaxation and subsidence of the heart and arteries
differ from their distension or diastole; and that the cause of the
distension, relaxation, and constriction, is not one and the same;
as contrary effects so must they rather acknowledge contrary causes;
as different movements they must have different motors; just as all
anatomists know that the flexion and extension of an extremity are
accomplished by opposite antagonist muscles, and contrary or diverse
motions are necessarily performed by contrary and diverse organs
instituted by nature for the purpose. Neither do I find the efficient
cause of the pulse aptly explained by this philosopher, when with
Aristotle he assumes the cause of the systole to be the same as that
of the diastole, viz. an effervescence of the blood due to a kind of
ebullition. For the pulse is a succession of sudden strokes and quick
percussions; but we know of no kind of fermentation or ebullition
in which the matter rises and falls in the twinkling of an eye; the
heaving is always gradual where the subsidence is notable. Besides,
in the body of a living animal laid open, we can with our eyes
perceive the ventricles of the heart both charged and distended by
the contraction of the auricles, and more or less increased in size
according to the charge; and farther, we can see that the distension of
the heart is rather a violent motion, the effect of an impulsion, and
not performed by any kind of attraction.

Some are of opinion that, as no kind of impulse of the nutritive juices
is required in vegetables, but that these are attracted by the parts
which require them, and flow in to take the place of what has been
lost; so neither is there any necessity for an impulse in animals, the
vegetative faculty in both working alike. But there is a difference
between plants and animals. In animals, a constant supply of warmth
is required to cherish the members, to maintain them in life by the
vivifying heat, and to restore parts injured from without. It is not
merely nutrition that has to be provided for.

So much for the circulation; any impediment, or perversion, or
excessive excitement of which, is followed by a host of dangerous
diseases and remarkable symptoms: in connexion with the veins--varices,
abcesses, pains, hemorrhoids, hemorrhages; in connexion with the
arteries--enlargements, phlegmons, severe and lancinating pains,
aneurisms, sarcoses, fluxions, sudden attacks of suffocation, asthmas,
stupors, apoplexies, and innumerable other affections. But this is
not the place to enter on the consideration of these; neither may I
say under what circumstances and how speedily some of these diseases,
that are even reputed incurable, are remedied and dispelled, as if by
enchantment. I shall have much to put forth in my Medical Observations
and Pathology, which, so far as I know, has as yet been observed by no

That I may afford you still more ample satisfaction, most learned
Riolanus, as you do not think there is a circulation in the vessels of
the mesentery, I shall conclude by proposing the following experiment:
throw a ligature round the porta close to the liver, in a living
animal, which is easily done. You will forthwith perceive the veins
below the ligature swelling in the same way as those of the arm when
the bleeding fillet is bound above the elbow; a circumstance which
will proclaim the course of the blood there. And as you still seem to
think that the blood can regurgitate from the veins into the arteries
by open anastomoses, let the vena cava be tied in a living animal near
the divarication of the crural veins, and immediately afterwards let an
artery be opened to give issue to the blood: you will soon observe the
whole of the blood discharged from all the veins, that of the ascending
cava among the number, with the single exception of the crural veins,
which will continue full; and this certainly could not happen were
there any retrograde passage for the blood from the veins to the
arteries by open anastomoses.




  _To Caspar Hofmann, M.D. Published at Nurenberg, in the “Spicilegium
  Illustrium Epistolarum ad Casp. Hofmannum.”_

Your opinion of me, my most learned Hofmann, so candidly given, and of
the motion and circulation of the blood, is extremely gratifying to me;
and I rejoice that I have been permitted to see and to converse with
a man so learned as yourself, whose friendship I as readily embrace
as I cordially return it. But I find that you have been pleased first
elaborately to inculpate me, and then to make me pay the penalty,
as having seemed to you “to have impeached and condemned Nature of
folly and error; and to have imputed to her the character of a most
clumsy and inefficient artificer, in suffering the blood to become
recrudescent, and making it return again and again to the heart in
order to be reconcocted, to grow effete as often in the general system;
thus uselessly spoiling the perfectly-made blood, merely to find
her in something to do.” But where or when anything of the kind was
ever said, or even imagined by me--by me, who, on the contrary, have
never lost an opportunity of expressing my admiration of the wisdom
and aptness and industry of Nature,--as you do not say, I am not a
little disturbed to find such things charged upon me by a man of sober
judgment like yourself. In my printed book, I do, indeed, assert that
the blood is incessantly moving out from the heart by the arteries
to the general system, and returning from this by the veins back to
the heart, and with such an ebb and flow, in such mass and quantity
that it must necessarily move in some way in a circuit. But if you
will be kind enough to refer to my eighth and ninth chapters you will
find it stated in so many words that I have purposely omitted to speak
of the concoction of the blood, and of the causes of this motion and
circulation, especially of the final cause. So much I have been anxious
to say, that I might purge myself in the eyes of a learned and much
respected man,--that I might feel absolved of the infamy of meriting
such censure. And I beg you to observe, my learned, my impartial
friend, if you would see with your own eyes the things I affirm in
respect of the circulation,--and this is the course which most beseems
an anatomist,--that I engage to comply with your wishes, whenever a fit
opportunity is afforded; but if you either decline this, or care not
by dissection to investigate the subject for yourself, let me beseech
you, I say, not to vilipend the industry of others, nor charge it to
them as a crime; do not derogate from the faith of an honest man, not
altogether foolish nor insane, who has had experience in such matters
for a long series of years.

Farewell, and beware! and act by me, as I have done by you; for what
you have written I receive as uttered in all candour and kindness. Be
sure, in writing to me in return, that you are animated by the same

  Nürnberg, May 20th, 1636.


_To Paul Marquard Slegel, of Hamburg_

I congratulate you much, most learned sir, on your excellent
commentary, in which you have replied in a very admirable manner to
Riolanus, the distinguished anatomist, and, as you say, formerly your
teacher: invincible truth has, indeed, taught the scholar to vanquish
the master. I was myself preparing a sponge for his most recent
arguments; but intent upon my work “On the Generation of Animals”
(which, but just come forth, I send to you), I have not had leisure
to produce it. And now I rather rejoice in the silence, as from your
supplement I perceive that it has led you to come forward with your
excellent reflections, to the common advantage of the world of letters.
For I see that in your most ornate book (I speak without flattery),
you have skilfully and nervously confuted all his machinations against
the circulation, and successfully thrown down the scaffolding of his
more recent opinions. I am, therefore, but little solicitous about
labouring at any ulterior answer. Many things might, indeed, be adduced
in confirmation of the truth, and several calculated to shed clearer
light on the art of medicine; but of these we shall perhaps see further
by and by.

Meantime, as Riolanus uses his utmost efforts to oppose the passage of
the blood into the left ventricle through the lungs, and brings it all
hither through the septum, and so vaunts himself upon having upset the
very foundations of the Harveian circulation (although I have nowhere
assumed such a basis for my doctrine; for there is a circulation in
many red-blooded animals that have no lungs), it may be well here to
relate an experiment which I lately tried in the presence of several
of my colleagues, and from the cogency of which there is no means
of escape for him. Having tied the pulmonary artery, the pulmonary
veins, and the aorta, in the body of a man who had been hanged, and
then opened the left ventricle of the heart, we passed a tube through
the vena cava into the right ventricle of the heart, and having, at
the same time, attached an ox’s bladder to the tube, in the same way
as a clyster-bag is usually made, we filled it nearly full of warm
water, and forcibly injected the fluid into the heart, so that the
greater part of a pound of water was thrown into the right auricle and
ventricle. The result was, that the right ventricle and auricle were
enormously distended, but not a drop of water or of blood made its
escape through the orifice in the left ventricle. The ligatures having
been undone, the same tube was passed into the pulmonary artery, and
a tight ligature having been put round it to prevent any reflux into
the right ventricle, the water in the bladder was now pushed towards
the lungs, upon which a torrent of the fluid, mixed with a quantity
of blood, immediately gushed forth from the perforation in the left
ventricle; so that a quantity of water, equal to that which was pressed
from the bladder into the lungs at each effort, instantly escaped by
the perforation mentioned. You may try this experiment as often as you
please; the result you will still find to be as I have stated it.

With this one experiment you may easily put an end to all Riolanus’s
altercations on the matter, to which he, nevertheless, so entirely
trusts, that, without adducing so much as a single experiment in
support of his views, he has been led to invent a new circulation, and
even so far to commit himself as to say that, unless the old doctrine
of the circulation[56] be overturned, his own is inadmissible. We may
pardon this distinguished individual for not having sooner discovered
a hidden truth; but that he, so well skilled in anatomy as he is,
should obstinately contend against a truth illustrated by the clearest
light of reason, this surely is argument of his envy--let me not call
it by any worse name. But, perhaps, we are still to find an excuse
for Riolanus, and to say, that what he has written is not so much of
his own motion, as in discharge of the duties of his office, and with
a view to stand well with his colleagues. As Dean of the College of
Paris, he was bound to see the physic of Galen kept in good repair,
and to admit no novelty into the school, without the most careful
winnowing, lest, as he says, the precepts and dogmata of physic should
be disturbed, and the pathology which has for so many years obtained
the sanction of all the learned in assigning the causes of disease, be
overthrown. He has been playing the part of the advocate, therefore,
rather than of the practised anatomist. But, as Aristotle tells us, it
is not less absurd to expect demonstrative arguments from the advocate,
than it is to look for persuasive arguments from the demonstrator or
teacher. For the sake of the old friendship subsisting between us,
moreover, and the high praise which he has lavished on the doctrine of
the circulation, I cannot find it in my heart to say anything severe of

  [56] i.e. Harvey’s Doctrine.

I therefore return to you, most learned Slegel, and say, that I wish
greatly I had been so full and explicit in what I have said on the
subject of anastomosis in my disquisition to Riolanus, as would have
left you with no doubts or scruples on the matter. I could wish, also,
that you had taken into account not only what I have there denied, but
likewise what I have asserted on the transference of the blood from the
arteries into the veins; especially as I there seem to have pointed
out some cause both for my inquiry and for my negation, to hint at a
certain cause. I confess, I say, nay, I even pointedly assert, that I
have never found any visible anastomoses. But this was particularly
said against Riolanus, who limited the circulation of the blood to
the larger vessels only, with which, therefore, these anastomoses, if
any such there were, must have been made conformable, viz. of ample
size, and distinctly visible. Although it be true, therefore, that I
totally deny all anastomoses of this description--anastomoses in the
way the word is commonly understood, and as the meaning has come down
to us from Galen, viz. a direct conjunction between the orifices of the
[visible] arteries and veins--I still admit, in the same disquisition,
that I have found what is equivalent to this in three places, namely,
in the plexus of the brain, in the spermatic or preparing arteries and
veins, and in the umbilical arteries and veins. I shall now, therefore,
for your sake, my learned friend, enter somewhat more at large into my
reasons for rejecting the vulgar notion of the anastomoses, and explain
my own conjectures concerning the mode of transition of the blood from
the minute arteries into the finest veins.

All reasonable medical men, both of ancient and modern times, have
believed in a mutual transfusion, or accession and recession of
the blood between the arteries and the veins; and for the sake of
permitting this, they have imagined certain inconspicuous openings, or
obscure foramina, through which the blood flowed hither and thither,
moving out of one vessel and returning to it again. Wherefore it is
not wonderful that Riolanus should in various places find that in the
ancients which is in harmony with the doctrine of a circulation. For
a circulation in such sort teaches nothing more than that the blood
flows incessantly from the veins into the arteries, and from the
arteries back again into the veins. But as the ancients thought that
this movement took place indeterminately, by a kind of accident, in one
and the same place, and through the same channels, I imagine that they
therefore found themselves compelled to adopt a system of anastomoses,
or fine mouths mutually conjoined, and serving both systems of vessels
indifferently. But the circulation which I discovered teaches clearly
that there is a necessary outward and backward flow of the blood, and
this at different times and places, and through other and yet other
channels and passages; that this flow is determinate also, and for the
sake of a certain end, and is accomplished in virtue of parts contrived
for the purpose with consummate forecast and most admirable art. So
that the doctrine of the motion of the blood from the veins into the
arteries, which antiquity only understood in the way of conjecture, and
which it also spoke of in confused and indefinite terms, was laid down
by me with its assured and necessary causes, and presents itself to
the understanding as a thing extremely clear, perfectly well arranged,
and of approved verity. And then, when I perceived that the blood was
transferred from the veins into the arteries through the medium of the
heart with singular art, and with the aid of an admirable apparatus of
valves, I imagined that the transference from the extremities of the
arteries into those of the veins could not be effected without some
other admirable artifice, at least wherever there was no transudation
through the pores of the flesh. I therefore held the anastomoses of the
ancients as fairly open to suspicion, both as they nowhere presented
themselves to our eyes, and as no sufficient reason was alleged for
anything of the kind.

Since, then, I find a transit from the arteries into the veins in
the three places which I have above mentioned, equivalent to the
anastomoses of the ancients, and even affording the farther security
against any regurgitation into the arteries of the blood once delivered
to the veins, and as a mechanism of such a kind is more elaborate and
better suited to the circulation of the blood, I have therefore thought
that the anastomoses imagined by the ancients were to be rejected.
But you will ask, what is this artifice? what these ducts? viz. the
small arteries, which are always much smaller--twice, even three times
smaller--than the veins which they accompany, which they approach
continually more and more, and within the tunics of which they are
finally lost. I have been therefore led to conceive that the blood
brought thus between the coats of the veins advanced for a certain way
along them, and that the same thing took place here which we observe in
the conjunction between the ureters and the bladder, and of the biliary
duct with the duodenum. The ureters insinuate themselves obliquely and
tortuously between the coats of the bladder, without anything in the
nature of an anastomosis, yet in such a manner as occasionally affords
a passage to blood, to pus, and to calculi; it is easy, moreover, to
fill the bladder through them with air or water; but by no effort can
you force anything from the bladder into them. I care not, however,
to make any question here of the etymology of words; for I am not
of opinion that it is the province of philosophy to infer aught as
to the works of nature from the signification of words, or to cite
anatomical disquisitions before the grammatical tribunal. Our business
is not so much to inquire what a word properly signifies, as how it is
commonly understood; for use and wont, as in so many other matters,
are greatly to be considered in the interpretation of words. It seems
to me, therefore, that we are to take especial care not to employ any
unusual words, or any common ones already familiarly used, in a sense
which is not in accordance with the meaning we purpose to attach to
them. You indeed counsel well when you say, “only make sure of the
thing, call it what you will.” But when we discover that a thing has
hitherto been indifferently or incorrectly explained (as the sequel
will show it to have been in the present case), I do not think that
the old appellation can ever be well applied to the new fact; by using
the old term you are apt to mislead where you desire to instruct. I
acknowledge, then, a transit of the blood from the arteries into the
veins, and that occasionally immediate, without any intervention of
soft parts; but it does not take place in the manner hitherto believed,
and as you yourself would have it, where you say that anastomoses,
correctly speaking, rather than an anastomosis, were required, namely,
that the vessels may be open on either hand, and give free passage to
the blood hither and thither. And hence it comes that you fail in the
right solution of the question, when you ask how it happens that with
the arteries as patent or pervious as the veins, the blood nevertheless
flows only from the former into the latter, never from the latter into
the former? For what you say of the impulse of the blood through the
arteries does not fully solve the difficulty in the present instance.
For if the aorta be tied near the left ventricle of the heart in
a living animal, and all the blood removed from the arteries, the
veins are still seen full of blood; so that it neither moves back
spontaneously into the arteries, nor can it be repelled into these by
any force, whilst even in a dead animal it nevertheless falls of its
own accord through the finest pores of the flesh and skin from superior
into inferior parts. The passage of the blood into the veins is,
indeed, effected by the impulse in question, and not by any dilatation
of these in the manner of bellows, by which the blood is drawn towards
them; but there are no anastomoses of the vessels by conjunction (per
copulam), in the way you mention, none where two vessels meeting are
conjoined by equal mouths. There is only an opening of the artery into
the vein, exactly in the same manner as the ureter opens into the
bladder (and the biliary duct opens into the jejunum), by which, whilst
the flow of urine is perfectly free towards the bladder, all reflux
into the smaller conduits is effectually prevented; the fuller the
bladder is, indeed, the more are the sides of the ureters compressed,
and the more effectual is all ascent of urine in them prevented. Now,
on this hypothesis, it is easy to render a reason for the experiment
which I have already mentioned. I add further, that I can in nowise
admit such anastomoses as are commonly imagined, inasmuch as the
arteries being always much smaller than the veins, it is impossible
that their sides can mutually conjoin in such a way as will allow of
their forming a common meatus; it seems matter of necessity that things
which join in this way should be of equal size. Lastly, these vessels
having made a certain circuit, must, at their terminations, encounter
one another; they would not, as it happens, proceed straight to the
extremities of the body. And the veins, on their part, if they were
conjoined with the arteries by mutual inosculations, would necessarily,
and by reason of the continuity of parts, pulsate like the arteries.

And now, that I may make an end of my writing, I say, that whilst I
think the industry of every one deserving of commendation, I do not
remember that I have anywhere bepraised mine own. You, however, most
excellent sir, I conceive have deserved high commendation, both for the
care you have bestowed on your disquisition on the liver of the ox, and
for the judgment you display in your observations. Go on, therefore,
as you are doing, and grace the republic of letters with the fruits of
your genius, for thus will you render a grateful service to all the
learned, and especially to

  Your loving

  Written in London, this 26th of March, 1651.


_To the very excellent John Nardi, of Florence_

I should have sent letters to you sooner, but our public troubles
in part, and in part the labour of putting to press my work “On the
Generation of Animals,” have hindered me from writing. And indeed I,
who receive your works--on the signal success of which I congratulate
you from my heart--and along with them most kind letters, do but very
little to one so distinguished as yourself in replying by a very short
epistle. I only write at this time that I may tell you how constantly
I think of you, and how truly I store up in my memory the grateful
remembrance of all your kindnesses and good offices to myself and to
my nephew, when we were each of us severally in Florence. I would
wish, illustrious sir, to have your news as soon as convenient:--what
you are about yourself, and what you think of this work of mine; for
I make no case of the opinions and criticisms of our pretenders to
scholarship, who have nothing but levity in their judgments, and indeed
are wont to praise none but their own productions. As soon as I know
that you are well, however, and that you live not unmindful of us here,
I propose to myself frequently to enjoy this intercourse by letter,
and I shall take care to transmit other books to you. I pray for many
and prosperous years to your Duke; and for yourself a long εὐημερία.
Farewell, most learned sir, and love in return.

  Yours, most truly,

  The 15th of July, 1651.


_In reply to R. Morison, M.D., of Paris_

ILLUSTRIOUS SIR,--The reason why your most kind letter has remained up
to this time unanswered is simply this, that the book of M. Pecquet,
upon which you ask my opinion, did not come into my hands until towards
the end of the past month. It stuck by the way, I imagine, with some
one, who, either through negligence, or desiring himself to see what
was newest, has for so long a time hindered me of the pleasure I have
had in the perusal. That you may, therefore, at once and clearly know
my opinion of this work, I say that I greatly commend the author for
his assiduity in dissection, for his dexterity in contriving new
experiments, and for the shrewdness which he still evinces in his
remarks upon them. With what labour do we attain to the hidden things
of truth when we take the averments of our senses as the guide which
God has given us for attaining to a knowledge of his works; avoiding
that specious path on which the eyesight is dazzled with the brilliancy
of mere reasoning, and so many are led to wrong conclusions, to
probabilities only, and too frequently to sophistical conjectures on

I further congratulate myself on his confirmation of my views of the
circulation of the blood by such lucid experiments and clear reasons.
I only wish he had observed that the heart has three kinds of motion,
namely, the systole, in which the organ contracts and expels the blood
contained in its cavities, and next, a movement, the opposite of the
former one, in which the fibres of the heart appropriated to motion are
relaxed. Now these two motions inhere in the substance of the heart
itself, just as they do in all other muscles. The remaining motion is
the diastole, in which the heart is distended by the blood impelled
from the auricles into the ventricles; and the ventricles, thus replete
and distended, are stimulated to contraction, and this motion always
precedes the systole, which follows immediately afterwards.

With regard to the lacteal veins discovered by Aselli, and by the
further diligence of Pecquet, who discovered the receptacle or
reservoir of the chyle, and traced the canals thence to the subclavian
veins, I shall tell you freely, since you ask me what I think of them.
I had already, in the course of my dissections, I venture to say
even before Aselli had published his book,[57] observed these white
canals, and plenty of milk in various parts of the body, especially
in the glands of younger animals, as in the mesentery, where glands
abound; and thence I thought came the pleasant taste of the thymus in
the calf and lamb, which, as you know, is called the sweetbread in
our vernacular tongue. But for various reasons, and led by several
experiments, I could never be brought to believe that that milky fluid
was chyle conducted hither from the intestines, and distributed to
all parts of the body for their nourishment; but that it was rather
met with occasionally and by accident, and proceeded from too ample a
supply of nourishment and a peculiar vigour of concoction; in virtue
of the same law of nature, in short, as that by which fat, marrow,
semen, hair, &c., are produced; even as in the due digestion of ulcers
pus is formed, which the nearer it approaches to the consistency of
milk, viz. as it is whiter, smoother, and more homogeneous, is held
more laudable, so that some of the ancients thought pus and milk were
of the same nature, or nearly allied. Wherefore, although there can be
no question of the existence of the vessels themselves, still I can by
no means agree with Aselli in considering them as chyliferous vessels,
and this especially for the reasons about to be given, which lead me
to a different conclusion. For the fluid contained in the lacteal
veins appears to me to be pure milk, such as is found in the lacteal
veins [the milk ducts] of the mammæ. Now it does not seem to me very
probable (any more than it does to Auzotius in his letter to Pecquet)
that the milk is chyle, and thus that the whole body is nourished
by means of milk. The reasons which lead to a contrary conclusion,
viz. that it is chyle, are not of such force as to compel my assent.
I should first desire to have it demonstrated to me by the clearest
reasonings, and the guarantee of experiments, that the fluid contained
in these vessels was chyle, which, brought hither from the intestines,
supplies nourishment to the whole body. For unless we are agreed upon
the first point, any ulterior, any more operose, discussion of their
nature, is in vain. But how can these vessels serve as conduits for the
whole of the chyle, or the nourishment of the body, when we see that
they are different in different animals? In some they proceed to the
liver, in others to the porta only, and in others still to neither of
these. In some creatures they are seen to be extremely numerous in the
pancreas; in others the thymus is crowded with them; in a third class,
again, nothing can be seen of them in either of these organs. In some
animals, indeed, such chyliferous canals are nowhere to be discovered
(vide Liceti Epist. xiii, tit. ii, p. 83, et Sennerti Praxeos, lib. v,
tit. 2, par. 3, cap. 1); neither do they exist in any at all times.
But the vessels which serve for nutrition must necessarily both exist
in all animals, and present themselves at all times; inasmuch as the
waste incurred by the ceaseless efflux of the spirits, and the wear and
tear of the parts of the body, can only be supplied by as ceaseless a
restoration or nutrition. And then, their very slender calibre seems
to render them not less inadequate to this duty than their structure
seems to unfit them for its performance: the smaller channels ought
plainly to end in larger ones, these in their turn in channels larger
still, and the whole to concentrate in one great trunk, which should
correspond in its dimensions to the aggregate capacity of all the
branches; just such an arrangement as may be seen to exist in the vena
portæ and its tributaries, and farther in the trunk of the tree, which
is equal to its roots. Wherefore, if the efferent canals of a fluid
must be equal in dimensions to the afferent canals of the same fluid,
the chyliferous ducts which Pecquet discovers in the thorax ought at
least to equal the two ureters in dimensions; otherwise they who drink
a gallon or more of one of the acidulous waters could not pass off
all this fluid in so short a space of time by these vessels into the
bladder. And truly, when we see the matter of the urine passing thus
copiously through the appropriate channels, I do not see how these
veins could preserve their milky colour, and the urine all the while
remain without a tinge of whiteness.

  [57] Published at Milan in 1622.

I add, too, that the chyle is neither in all animals, nor at all
times, of the consistency and colour of milk; and therefore did these
vessels carry chyle, they could not always (which nevertheless they
do) contain a white fluid in their interior, but would sometimes be
coloured yellow, green, or of some other hue (in the same way as the
urine is affected, and acquires different colours from eating rhubarb,
asparagus, figs, &c.); or otherwise, when large quantities of mineral
water were drunk, they would be deprived of almost all colour. Besides,
did that white matter pass from the intestines into those canals, or
were it attracted from the intestines, the same fluid ought certainly
to be discovered somewhere within the intestines themselves, or in
their spongy tunics; for it does not seem probable that any fluid by
bare and rapid percolation of the intestines could assume a new nature,
and be changed into milk. Moreover, were the chyle only filtered
through the tunics of the intestines, it ought surely to retain some
traces of its original nature, and resemble in colour and smell the
fluid contained in the intestines; it ought to smell offensively at
least; for whatever is contained in the intestines is tinged with bile,
and smells unpleasantly. Some have consequently thought that the body
was nourished by means of chyle raised into attenuated vapour, because
vapours exhaling in the alembic, even from fœtid matters, often do not
smell amiss.

The learned Pecquet ascribes the motion of this milky fluid to
respiration. For my own part, though strongly tempted to do otherwise,
I shall say nothing upon this topic until we are agreed as to what
the fluid is. But were we to concede the point (which Pecquet takes
for granted without any sufficient reason in the shape of argument),
that chyle was continually transported by the canals in question from
the intestines to the subclavian veins, in which the vessels he has
lately discovered terminate, we should have to say that the chyle
before reaching the heart was mixed with the blood which is about
to enter the right side of the organ, and that it there obtains a
further concoction. But what, some one might with as good reason ask,
should hinder it from passing into the porta, then into the liver,
and thence into the cava, in conformity with the arrangement which
Aselli and others are said to have found? Why, indeed, should we not
as well believe that the chyle enters the mouths of the mesenteric
veins, and in this way becomes immediately mingled with the blood,
where it might receive digestion and perfection from the heat, and
serve for the nutrition of all the parts? For the heart itself can be
accounted of higher importance than other parts, can be termed the
source of heat and of life, upon no other grounds than as it contains
a larger quantity of blood in its cavities, where, as Aristotle says,
the blood is not contained in veins as it is in other parts, but in
an ample sinus and cistern, as it were. And that the thing is so in
fact, I find an argument in the distribution of innumerable arteries
and veins to the intestines, more than to any other part of the body,
in the same way as the uterus abounds with blood-vessels during the
period of pregnancy. For nature never acts inconsiderately. In all
the red-blooded animals, consequently, which require [abundant]
nourishment, we find a copious distribution of mesenteric vessels;
but lacteal veins we discover in but a few, and even in these not
constantly. Wherefore, if we are to judge of the uses of parts as we
meet with them in general and in the greater number of animals, beyond
all doubt those filaments of a white colour, and very like the fibres
of a spider’s web, are not instituted for the purpose of transporting
nourishment, neither is the fluid they contain to be designated by the
name of chyle; the mesenteric vessels are rather destined to the duty
in question. Because, of that whence an animal is constituted, by that
must it necessarily grow, and by that consequently be nourished; for
the nutritive and augmentative faculties, or nutrition and growth,
are essentially the same. An animal, therefore, naturally grows in the
same manner as it receives immediate nutriment from the first. Now it
is a most certain fact (as I have shown elsewhere) that the embryos
of all red-blooded animals are nourished by means of the umbilical
vessels from the mother, and this in virtue of the circulation of the
blood. They are not nourished, however, immediately by the blood, as
many have imagined, but after the manner of the chick in ovo, which
is first nourished by the albumen, and then by the vitellus, which
is finally drawn into and included within the abdomen of the chick.
All the umbilical vessels, however, are inserted into the liver, or
at all events pass through it, even in those animals whose umbilical
vessels enter the vena portæ, as in the chick, in which the vessels
proceeding from the yelk always so terminate. In the selfsame way,
therefore, as the chick is nourished from a nutriment, (viz. the
albumen and vitellus,) previously prepared, even so does it continue
to be nourished through the whole course of its independent existence.
And the same thing, as I have elsewhere shown, is common to all embryos
whatsoever: the nourishment, mingled with the blood, is transmitted
through their veins to the heart, whence moving on by the arteries,
it is carried to every part of the body. The fœtus when born, when
thrown upon its own resources, and no longer immediately nourished by
the mother, makes use of its stomach and intestines just as the chick
makes use of the contents of the egg, and vegetables make use of the
ground whence they derive concocted nutriment. For even as the chick
at the commencement obtained its nourishment from the egg, by means of
the umbilical vessels (arteries and veins) and the circulation of the
blood, so does it subsequently, and when it has escaped from the shell,
receive nourishment by the mesenteric veins; so that in either way the
chyle passes through the same channels, and takes its route by the
same path through the liver. Nor do I see any reason why the route by
which the chyle is carried in one animal should not be that by which it
is carried in all animals whatsoever; nor indeed, if a circulation of
the blood be necessary in this matter, as it really is, that there is
any need for inventing another way.

I must say that I greatly prize the industry of the learned Pecquet,
and make much of the receptacle which he has discovered; still it does
not present itself to me as of such importance as to force me from
the opinion I have already given; for I have myself found several
receptacles of milk in young animals; and in the human embryo I
have found the thymus so distended with milk, that suspicions of an
imposthume were at first sight excited, and I was disposed to believe
that the lungs were in a state of suppuration, for the mass of the
thymus looked actually larger than the lungs themselves. Frequently,
too, I have found a quantity of milk in the nipples of new-born
infants, as also in the breasts of young men who were very lusty. I
have also met with a receptacle full of milk in the body of a fat and
large deer, in the situation where Pecquet indicates his receptacle, of
such a size that it might readily have been compared to the abomasus,
or read of the animal.

These observations, learned sir, have I made at this time in answer to
your letter, that I might show my readiness to comply with your wishes.

Pray present my most kind wishes to Dr. Pecquet and to Dr. Gayant.
Farewell, and believe me to be, very affectionately and respectfully,


  London, the 28th April, 1652.


_To the most excellent and learned John Nardi, of Florence_

DISTINGUISHED AND ACCOMPLISHED SIR,--The arrival of your letter lately
gave me the liveliest pleasure, and the receipt at the same time of
your learned comments upon Lucretius satisfied me that you are not
only living and well, but that you are at work among the sacred things
of Apollo. I do indeed rejoice to see truly learned men everywhere
illustrating the republic of letters, even in the present age, in
which the crowd of foolish scribblers is scarcely less than the swarms
of flies in the height of summer, and threatens with their crude and
flimsy productions to stifle us as with smoke. Among other things that
delighted me greatly in your book was that part where I see you ascribe
plague almost to the same efficient cause as I do animal generation.
Still it must be confessed that it is difficult to explain how the
idea, or form, or vital principle should be transfused from the genitor
to the genetrix, and from her transmitted to the conception or ovum,
and thence to the fœtus, and in this produce not only an image of the
genitor, or an external species, but also various peculiarities or
accidents, such as disposition, vices, hereditary diseases, nævi or
mother-marks, &c. All of these accidents must inhere in the geniture
and semen, and accompany that specific thing, by whatever name you
call it, from which an animal is not only produced, but by which it is
afterwards governed, and to the end of its life preserved. As all this,
I say, is not readily accounted for, so do I hold it scarcely less
difficult to conceive how pestilence or leprosy should be communicated
to a distance by contagion, by a zymotic element contained in woollen
or linen things, household furniture, even the walls of a house,
cement, rubbish, &c., as we find it stated in the fourteenth chapter
of Leviticus. How, I ask, can contagion, long lurking in such things,
leave them in fine, and after a long lapse of time produce its like
in another body? Nor in one or two only, but in many, without respect
of strength, sex, age, temperament, or mode of life, and with such
violence that the evil can by no art be stayed or mitigated. Truly
it does not seem less likely that form, or soul, or idea, whether
this be held substantive or accidental, should be transferred to
something else, whence an animal at length emerges, all as if it
had been produced on purpose, and to a certain end, with foresight,
intelligence, and divine art.

These are among the number of more abstruse matters, and demand your
ingenuity, most learned Nardi. Nor need you plead in excuse your
advanced life; I myself, although verging on my eightieth year, and
sorely failed in bodily strength, nevertheless feel my mind still
vigorous, so that I continue to give myself up with the greatest
pleasure to studies of this kind. I send you along with these, three
books upon the subject you name.[58] If you will mention my name to
his Serene Highness the Duke of Tuscany, with thankfulness for the
distinguished honour he did me when I was formerly in Florence, and add
my wishes for his safety and prosperity, you will do a very kind thing

  [58] [Nardi had written to Harvey requesting him to select a few
  of the publications which should give a faithful narrative of the
  distractions that had but lately agitated England.]

  Your devoted and very attached friend,

  30th Nov. 1653.


_To John Daniel Horst, principal Physician of Hesse-Darmstadt_

EXCELLENT SIR,--I am much pleased to find, that in spite of the long
time that has passed, and the distance that separates us, you have
not yet lost me from your memory, and I could wish that it lay in my
power to answer all your inquiries. But, indeed, my age does not permit
me to have this pleasure, for I am not only far stricken in years,
but am afflicted with more and more indifferent health. With regard
to the opinions of Riolanus, and his decision as to the circulation
of the blood, it is very obvious that he makes vast throes in the
production of vast trifles; nor do I see that he has as yet satisfied
a single individual with his figments. Slegel wrote well and modestly,
and, had the fates allowed, would undoubtedly have answered his
arguments and reproaches also. But Slegel as I learn, and grieve to
learn, died some months ago. As to what you ask of me, in reference
to the so-called lacteal veins and thoracic ducts, I reply, that it
requires good eyes, and a mind free from other anxieties, to come to
any definite conclusion in regard to these extremely minute vessels;
to me, however, as I have just said, neither of these requisites is
given. About two years ago, when asked my opinion on the same subject,
I replied at length, and to the effect that it was not sufficiently
determined whether it was chyle or one of the thicker constituents
of milk, destined speedily to pass into fat, which flowed in these
white vessels; and further that the vessels themselves are wanting
in several animals, namely, birds and fishes, though it seems most
probable that these creatures are nourished upon the same principles as
quadrupeds; nor can any sufficient reason be rendered why in the embryo
all nutriment, carried by the umbilical vein, should pass through the
liver, but that this should not happen when the fœtus is freed from the
prison of the womb, and made independent. Besides, the thoracic duct
itself, and the orifice by which it communicates with the subclavian
vein, appear too small and narrow to suffice for the transmission of
all the supplies required by the body. And I have asked myself farther,
why such numbers of blood-vessels, arteries, and veins should be sent
to the intestines if there were nothing to be brought back from thence?
especially as these are mere membraneous parts, and on this account
require a smaller supply of blood.

These and other observations of the same tenor I have already
made,--not as being obstinately wedded to my own opinion, but that I
might find out what could reasonably be urged to the contrary by the
advocates of the new views. I am ready to award the highest praise
to Pecquet and others for their singular industry in searching out
the truth; nor do I doubt but that many things still lie hidden in
Democritus’s well that are destined to be drawn up into the light by
the indefatigable diligence of coming ages. So much do I say at this
time, which, I trust, with your known kindness, you will take in good
part. Farewell, learned friend; live happily, and hold me always

  Yours, most affectionately,

  London, 1st February, 1654-5.


_To the distinguished and learned John Dan. Horst, principal Physician
at the Court of Hesse-Darmstadt_

MOST EXCELLENT SIR,--Advanced age, which unfits us for the
investigation of novel subtleties, and the mind which inclines to
repose after the fatigues of lengthened labours, prevent me from mixing
myself up with the investigation of these new and difficult questions:
so far am I from courting the office of umpire in this dispute! I was
anxious to do you a pleasure lately, when, in reply to your request,
I sent you the substance of what I had formerly written to a Parisian
physician as my ideas on the lacteal veins and thoracic ducts.[59]
Not, indeed, that I was certain of the opinion then delivered, but
that I might place these objections such as they were before those who
fancy that when they have made a certain progress in discovery all is
revealed by them.

  [59] [Pecquet described the duct as dividing into two branches, one
  for each subclavian vein.]

With reference to your letters in reply, however, and in so far as
the collection of milky fluid in the vessels of Aselli is concerned,
I have not ascribed it to accident, and as if there were not certain
assignable causes for its existence; but I have denied that it was
found at all times in all animals, as the constant tenor of nutrition
would seem to require. Nor is it requisite that a matter, already
thin and much diluted, and which is to become fat after the ulterior
concoction, should concrete in the dead animal. The instance of pus, I
have adduced only incidentally and collaterally. The hinge upon which
our whole discussion turns is the assumption that the fluid contained
in the lacteal vessels of Aselli is chyle. This position I certainly
do not think you demonstrate satisfactorily, when you say that chyle
must be educed from the intestines, and that it can by no means be
carried off by the arteries, veins, or nerves; and thence conclude that
this function must be performed by the lacteals. I, however, can see no
reason wherefore the innumerable veins which traverse the intestines at
every point, and return to the heart the blood which they have received
from the arteries, should not, at the same time, also suck up the chyle
which penetrates the parts, and so transmit it to the heart; and this
the rather, as it seems probable that some chyle passes immediately
from the stomach before its contents have escaped into the intestines,
(or how account for the rapid recovery of the spirits and strength in
cases of fainting?) although no lacteals are distributed to the stomach.

With regard to the letter which you inform me you have addressed to
Bartholin, I do not doubt of his replying to you as you desire; nor
is there any occasion wherefore I should trouble you farther on that
topic. I only say (keeping silence as to any other channels), that
the nutritive juice might be as readily transported by the uterine
arteries, and distilled into the uterus, as watery fluid is carried
by the emulgent arteries to the kidneys. Nor can this juice be spoken
of as preternatural; neither ought it to be compared to the vagitus
uterinus, seeing that in pregnant women the fluid is always present,
the vagitus an incident of very rare occurrence. What you say of the
excrements of new-born infants differing from those of the child that
has once tasted milk I do not admit; for except in the particular of
colour, I scarcely perceive any difference between them, and conceive
that the black hue may fairly be ascribed to the long stay of the fæces
in the bowels.

Your proposal that I should attempt a solution of the true use of these
newly-discovered ducts, is an undertaking of greater difficulty than
comports with the old man far advanced in years, and occupied with
other cares: nor can such a task be well entrusted to several hands,
were even such assistance as you indicate at my command[60]; but it is
not; Highmore does not live in our neighbourhood, and I have not seen
him for a period of some seven years. So much I write at present, most
learned sir, trusting it will be taken in good part as coming from

  [60] [Horst, in the letter to which the above is an answer, had said,
  “Nobilissime Harveie, &c. Most noble Harvey, I only wish you could
  snatch the leisure to explain to the world the true use of these
  lymphatic and thoracic ducts. You have many illustrious scholars,
  particularly Highmore, with whose assistance it were easy to solve
  all doubts.”]

  Very sincerely and respectfully,

  London, 13th July, 1655 (old style).


_To the very learned John Nardi, of Florence, a man distinguished alike
for his virtues, life, and erudition_

MOST EXCELLENT SIR,--I lately received your most agreeable letter,
from which I am equally delighted to learn that you are well, that
you go on prosperously, and labour strenuously in our chosen studies.
But I am not informed whether my letter in reply to yours, along
with a few books forwarded at the same time, have come to hand or
not. I should be happy to have news on this head at your earliest
convenience, and also to be made acquainted with the progress you make
in your “Noctes Geniales,” and other contemplated works. For I am
used to solace my declining years, and to refresh my understanding,
jaded with the trifles of every-day life, by reading the best works of
this description. I have again to return you my best thanks for your
friendly offices to my nephew when at Florence in former years; and on
the arrival in Italy of another of my nephews (who is the bearer of
this letter), I entreat you very earnestly that you will be pleased
most kindly to favour him with any assistance or advice of which he
may stand in need. For thus will you indeed do that which will be very
gratifying to me. Farewell, most accomplished sir, and deign to cherish
the memory of our friendship, as does most truly the admirer of all
your virtues,


  London, Oct. 25th, in the year of the Christian era, 1655.


_To the distinguished and accomplished John Vlackveld, Physician at

LEARNED SIR,--Your much esteemed letter reached me safely, in which you
not only exhibit your kind consideration of me, but display a singular
zeal in the cultivation of our art.

It is even so. Nature is nowhere accustomed more openly to display her
secret mysteries than in cases where she shows traces of her workings
apart from the beaten path; nor is there any better way to advance the
proper practice of medicine than to give our minds to the discovery
of the usual law of nature, by the careful investigation of cases of
rarer forms of disease. For it has been found in almost all things,
that what they contain of useful or of applicable, is hardly perceived
unless we are deprived of them, or they become deranged in some way.
The case of the plasterer[61] to which you refer is indeed a curious
one, and might supply a text for a lengthened commentary by way of
illustration. But it is in vain that you apply the spur to urge me, at
my present age, not mature merely but declining, to gird myself for any
new investigation. For I now consider myself entitled to my discharge
from duty. It will, however, always be a pleasant sight for me to
see distinguished men like yourself engaged in this honorable arena.
Farewell, most learned sir, and whatever you do, still love

  [61] [Vlackveld had sent to Harvey the particulars of a case of
  diseased bladder, in which that viscus was found after death not
  larger than “a walnut with the husk,” its walls as thick as the
  thickness of the little finger, and its inner surface ulcerated.]

  Yours, most respectfully,

  London, 24th April, 1657.





                    AND IRELAND

[This account first appeared in the work of Dr. Betts, entitled: “De
Ortu et Natura Sanguinis,” 8vo, London, 1669, the MS. having been
presented to Betts by Mr. Michael Harvey, nephew of the author, with
whom Betts was on terms of intimacy.]


Thomas Parr, a poor countryman, born near Winnington, in the county
of Salop, died on the 14th of November, in the year of grace 1635,
after having lived one hundred and fifty-two years and nine months,
and survived nine princes. This poor man, having been visited by the
illustrious Earl of Arundel when he chanced to have business in these
parts, (his lordship being moved to the visit by the fame of a thing so
incredible,) was brought by him from the country to London; and, having
been most kindly treated by the earl both on the journey and during a
residence in his own house, was presented as a remarkable sight to his
Majesty the King.

Having made an examination of the body of this aged individual, by
command of his Majesty, several of whose principal physicians were
present, the following particulars were noted:

The body was muscular, the chest hairy, and the hair on the fore-arms
still black; the legs, however, were without hair, and smooth.

The organs of generation were healthy, the penis neither retracted nor
extenuated, nor the scrotum filled with any serous infiltration, as
happens so commonly among the decrepid; the testes, too, were sound
and large; so that it seemed not improbable that the common report
was true, viz. that he did public penance under a conviction for
incontinence, after he had passed his hundredth year; and his wife,
whom he had married as a widow in his hundred-and-twentieth year, did
not deny that he had intercourse with her after the manner of other
husbands with their wives, nor until about twelve years back had he
ceased to embrace her frequently.

The chest was broad and ample; the lungs, nowise fungous, adhered,
especially on the right side, by fibrous bands to the ribs. They were
much loaded with blood, as we find them in cases of peripneumony, so
that until the blood was squeezed out they looked rather blackish.
Shortly before his death I had observed that the face was livid, and he
suffered from difficult breathing and orthopnœa. This was the reason
why the axillæ and chest continued to retain their heat long after his
death: this and other signs that present themselves in cases of death
from suffocation were observed in the body.

We judged, indeed, that he had died suffocated, through inability to
breathe, and this view was confirmed by all the physicians present, and
reported to the King. When the blood was expressed, and the lungs were
wiped, their substance was beheld of a white and almost milky hue.

The heart was large, and thick, and fibrous, and contained a
considerable quantity of adhering fat, both in its circumference and
over its septum. The blood in the heart, of a black colour, was dilute,
and scarcely coagulated; in the right ventricle alone some small clots
were discovered.

In raising the sternum, the cartilages of the ribs were not found
harder or converted into bone in any greater degree than they are in
ordinary men; on the contrary, they were soft and flexible.

The intestines were perfectly sound, fleshy, and strong, and so was
the stomach: the small intestines presented several constrictions,
like rings, and were muscular. Whence it came that, by day or night,
observing no rules or regular times for eating, he was ready to
discuss any kind of eatable that was at hand; his ordinary diet
consisting of sub-rancid cheese, and milk in every form, coarse and
hard bread, and small drink, generally sour whey. On this sorry fare,
but living in his home, free from care, did this poor man attain to
such length of days. He even ate something about midnight shortly
before his death.

The kidneys were bedded in fat, and in themselves sufficiently healthy;
on their anterior aspects, however, they contained several small watery
abscesses or serous collections, one of which, the size of a hen’s
egg, containing a yellow fluid in a proper cyst, had made a rounded
depression in the substance of the kidney. To this some were disposed
to ascribe the suppression of urine under which the old man had
laboured shortly before his death; whilst others, and with greater show
of likelihood, ascribed it to the great regurgitation of serum upon the

There was no appearance of stone either in the kidneys or bladder.

The mesentery was loaded with fat, and the colon, with the omentum,
which was likewise fat, was attached to the liver, near the fundus of
the gall-bladder; in like manner the colon was adherent from this point
posteriorly with the peritoneum.

The viscera were healthy; they only looked somewhat white externally,
as they would have done had they been parboiled; internally they were
(like the blood) of the colour of dark gore.

The spleen was very small, scarcely equalling one of the kidneys in

All the internal parts, in a word, appeared so healthy, that had
nothing happened to interfere with the old man’s habits of life, he
might perhaps have escaped paying the debt due to nature for some
little time longer.

The cause of death seemed fairly referrible to a sudden change in the
non-naturals, the chief mischief being connected with the change of
air, which through the whole course of life had been inhaled of perfect
purity,--light, cool, and mobile, whereby the præcordia and lungs were
more freely ventilated and cooled; but in this great advantage, in this
grand cherisher of life this city is especially destitute; a city whose
grand characteristic is an immense concourse of men and animals, and
where ditches abound, and filth and offal lie scattered about, to say
nothing of the smoke engendered by the general use of sulphureous coal
as fuel, whereby the air is at all times rendered heavy, but much more
so in the autumn than at any other season. Such an atmosphere could
not have been found otherwise than insalubrious to one coming from the
open, sunny, and healthy region of Salop; it must have been especially
so to one already aged and infirm.

And then for one hitherto used to live on food unvaried in kind, and
very simple in its nature, to be set at a table loaded with variety
of viands, and tempted not only to eat more than wont, but to partake
of strong drink, it must needs fall out that the functions of all the
natural organs would become deranged. Whence the stomach at length
failing, and the excretions long retained, the work of concoction
proceeding languidly, the liver getting loaded, the blood stagnating
in the veins, the spirits frozen, the heart, the source of life,
oppressed, the lungs infarcted, and made impervious to the ambient air,
the general habit rendered more compact, so that it could no longer
exhale or perspire--no wonder that the soul, little content with such a
prison, took its flight.

The brain was healthy, very firm and hard to the touch; hence, shortly
before his death, although he had been blind for twenty years, he
heard extremely well, understood all that was said to him, answered
immediately to questions, and had perfect apprehension of any matter
in hand; he was also accustomed to walk about, slightly supported
between two persons. His memory, however, was greatly impaired, so
that he scarcely recollected anything of what had happened to him when
he was a young man, nothing of public incidents, or of the kings or
nobles who had made a figure, or of the wars or troubles of his earlier
life, or of the manners of society, or of the prices of things--in a
word, of any of the ordinary incidents which men are wont to retain in
their memories. He only recollected the events of the last few years.
Nevertheless, he was accustomed, even in his hundred and thirtieth
year, to engage lustily in every kind of agricultural labour, whereby
he earned his bread, and he had even then the strength required to
thrash the corn.


_Extracted from the Registry of the Prerogative Court of Canterbury_

In the name of the Almighty and Eternal God Amen I WILLIAM HARVEY of
London Doctor of Physicke doe by these presents make and ordaine this
my last Will and testament in manner and forme following Revoking
hereby all former and other wills and testaments whatsoever Imprimis I
doe most humbly render my soule to Him that gave it and to my blessed
Lord and Saviour Christ Jesus and my bodie to the Earth to be buried
at the discretion of my executor herein after named The personall
estate which at the time of my decease I shalbe in any way possessed
of either in Law or equitie be it in goods householdstuffe readie
moneys debts duties arrearages of rents or any other wayes whatsoever
and whereof I shall not by this present will or by some Codicill to
be hereunto annexed make a particular gift and disposition I doe
after my debts Funeralls and Legacies paid and discharged give and
bequeath the same vnto my loving brother Mr. Eliab Harvey merchant of
London whome I make Executor of this my last will and testament And
whereas I have lately purchased certaine lands in Northamptonshire or
thereabouts commonly knowne by the name of Oxon grounds and formerly
belonging vnto to the Earl of Manchester and certaine other grounds in
Leicestershire commonly called or knowne by the name of Baron Parke
and sometime heretofore belonging vnto Sir Henry Hastings Knight both
which purchases were made in the name of several persons nominated
and trusted by me and by two severall deeds of declaracon vnder the
handes and seales of all persons any waye parties or privies to the
said trusts are declared to be first vpon trust and to the intent
that I should be permitted to enioye all the rents and profits and
the benefit of the collaterall securitie during my life and from and
after my decease Then upon trust and for the benefit of such person and
persons and of and for such estate and estates and Interests And for
raysing and payment of such summe and summes of Money Rents Charges
Annuities and yearly payments to and for such purposes as from time
to time by any writing or writings to be by me signed and sealed in
the presence of Two or more credible witnesses or by my last will and
testament in writing should declare limit direct or appoint And further
in trust that the said Mannors and lands and everie part thereof
together with the Collaterall securitie should be assigned conveyed
and assured vnto such persons and for suche Estates as the same should
by me be limited and directed charged and chargeable nevertheles with
all Annuities rents and summes of money by me limited and appointed
if any such shalbe And in default of such appointment then to Eliab
Harvey his heires executors and Assignes or to such as he or they shall
nominate as by the said two deeds of declaracon both of them bearing
date the tenth day of July in the year of our Lord God one Thousand
sixe hundred Fiftie and one more at large it doth appeare I doe now
hereby declare limit direct and appoint that with all convenient speed
after my decease there shalbe raised satisfied and paid these severall
summes of money Rents Charges and Annuities herein after expressed and
likewise all such other summes of Money Rents Charges or Annuities
which at any time hereafter in any Codicill to be hereunto annexed
shall happen to be limited or expressed And first I appoint so much
money to be raised and laid out vpon that building which I have already
begun to erect within the Colledge of Physicians in London as will
serve to finish the same according to the designe already made Item I
give and bequeath vnto my lo sister in Law Mrs Eliab Harvey one hundred
pounds to buy something to keepe in remembrance of me Item I give to my
Niece Mary Pratt all that Linnen householdstuffe and furniture which
I have at Coome neere Croydon for the vse of Will Foulkes and to whom
his keeping shalbe assigned after her death or before me at any time
Item I give vnto my Niece Mary West and her daughter Amy West halfe
the Linnen I shall leave at London in my chests and Chambers together
with all my plate excepting my Coffey pot Item I give to my lo sister
Eliab all the other halfe of my Linnen which I shall leave behind me
Item I give to my lo sister Daniell at Lambeth and to everie one of
her children severally the summe of fiftie pounds Item I give to my lo
Coosin Mr Heneage Finch for his paines counsell and advice about the
contriving of this my will one hundred pounds Item I give to all my
little Godchildren Nieces and Nephews severally to everie one Fiftie
pounds Item I give and bequeath to the towne of Foulkestone where I
was borne two hundred pounds to be bestowed by the advice of the Mayor
thereof and my Executor for the best vse of the poore Item I give to
the poore of Christ hospitall in Smithfield thirtie pounds Item I
give to Will Harvey my godsonne the sonne of my brother Mich Harvey
deceased one hundred pounds and to his brother Michaell Fiftie pounds
Item I give to my Nephew Tho Cullen and his children one hundred pounds
and to his brother my godsonne Will Cullen one hundred pounds Item I
give to my Nephew Jhon Harvey the sonne of my lo brother Tho Harvey
deceased two hundred pounds Item I give to my Servant John Raby for
his diligence in my service and sicknesse twentie pounds And to Alice
Garth my Servant Tenne pounds over and above what I am already owing
unto her by my bill which was her mistresses legacie Item I give among
the poor children of Amy Rigdon daughter of my lo vncle Mr Tho Halke
twentie pounds Item among other my poorest kindred one hundred pounds
to be distributed at the appointment of my Executor Item I give among
the servants of my sister Dan at my Funeralls Five pounds And likewise
among the servants of my Nephew Dan Harvey at Coome as much Item I
give to my Cousin Mary Tomes Fifty pounds Item I give to my lo Friend
Mr Prestwood one hundred pounds Item I give to everie one of my lo
brother Eliab his sonnes and daughters severally Fiftie pounds apiece
All which legacies and gifts aforesaid are chiefly to buy something to
keepe in remembrance of me Item I give among the servants of my brother
Eliab which shalbe dwelling with him at the time of my decease tenne
pounds Furthermore I give and bequeath vnto my Sister Eliabs Sister Mrs
Coventrey a widowe during her natural life the yearly rent or summe of
twentie pounds Item I give to my Niece Mary West during her naturall
life the yearly rent or summe of Fortie pounds Item I give for the vse
and behoofe and better ordering of Will Foulkes for and during the
term of his life vnto my Niece Mary Pratt the yearly rent of tenne
pounds which summe if it happen my said Niece shall dye before him I
desire may be paid to them to whome his keeping shalbe appointed Item
I will that the twentie pounds which I yearly allowe him my brother
Galen Browne may be continued as a legacie from his sister during
his naturall life Item I will that the payments to Mr Samuel Fentons
children out of the profits of Buckholt Lease be orderly performed
as my deere deceased lo wife gave order so long as that lease shall
stand good Item I give vnto Alice Garth during her naturall life the
yearly rent or summe of twentie pounds Item To John Raby during his
naturall life sixteene pounds yearly rent All which yearly rents or
summes to be paid halfe yearly at the two most vsuall feasts in the
yeare viz Michaelmas and our Lady day without any deduction for or by
reason of any manner of taxes to be any way hereafter imposed The first
payment of all the said rents or Annuities respectively to beginne at
such of those feasts which shall first happen next after my decease
Thus I give the remainder of my lands vnto my lo brother Eliab and his
heires All my legacies and gifts &c. being performed and discharged
Touching my bookes and householdstuffe Pictures and apparell of which
I have not already disposed I give to the Colledge of Physicians all
my bookes and papers and my best Persia long Carpet and my blue sattin
imbroyedyed Cushion one paire of brasse Andirons with fireshovell and
tongues of brasse for the ornament of the meeting roome I have erected
for that purpose Item I give my velvet gowne to my lo friend Mr Doctor
Scarbrough desiring him and my lo friend Mr Doctor Ent to looke over
those scattered remnant of my poore Librarie and what bookes papers
or rare collections they shall thinke fit to present to the Colledge
and the rest to be Sold and with the money buy better And for their
paines I give to Mr Doctor Ent all the presses and shelves he please
to make use of and five pounds to buy him a ring to keepe or weare in
remembrance of me And to Dr Scarbrough All my little silver instruments
of surgerie Item I give all my Chamber furniture tables bed bedding
hangings which I have at Lambeth to my Sister Dan and her daughter
Sarah And all that at London to my lo Sister Eliab and her daughter or
my godsonne Eliab as she shall appoint Lastly I desire my executor to
assigne over the custode of Will Fowkes after the death of my Niece
Mary Pratt if she happen to dye before him vnto the Sister of the said
William my Niece Mary West Thus I have finished my last Will in three
pages two of them written with own hand and my name subscribed to
everie one with my hand and seal to the last


       *       *       *       *       *

Signed sealed and published as the last will and testament of me
William Harvey In the presence of us Edward Dering Henneage Finch
Richard Flud Francis Finche Item I have since written a Codicill with
my owne hand in a sheet of paper to be added hereto with my name
thereto subscribed and my seale.

ITEM I will that the sumes and charges here specified be added and
annexed vnto my last will and testament published heretofore in the
presence of Sir Edward Dering and Mr. Henneage Finch and others and as
a Codicill by my Executor in like manner to be performed whereby I will
and bequeath to John Denn sonne of Vincent Denne the summe of thirtie
pounds Item to my good friend Mr Tho Hobbs to buy something to keepe
in remembrance of me tenne pounds and to Mr Kennersley in like manner
twentie pounds Item what moneys shalbe due to me from Mr. Hen Thompson
his fees being discharged I give to my friend Mr Prestwood Item what
money is of mine viz one hundred pounds in the hands of my Cosin Rigdon
I give halfe thereof to him towards the marriage of his niece and the
other halfe to be given to Mrs Coventrey for her sonne Walter when he
shall come of yeares and for vse my Cosin Rigdon giving securitie I
would he should pay none Item what money shalbe due to me and Alice
Garth my servant on a pawne now in the hands of Mr Prestwood I will
after my decease shall all be given my said servant for her diligence
about me in my siknesse and service both interest and principall Item
if in case it so fall out that my good friend Mrs Coventrey during her
widowhood shall not dyet on freecost with my brother or Sister Eliab
Harvey Then I will and bequeath to her one hundred marke yearly during
her widowhood Item I will and bequeath to my loving Cosin Mr Henneage
Finch (more than heretofore) to be for my godsonne Will Finche one
hundred pounds Item I will and bequeath yearly during her life a rent
of thirtie pounds vnto Mrs Jane Nevison Widdowe in case she shall not
preferre her selfe in marriage to be paid quarterly by even porcons
the first to beginn at Christmas Michaelmas or Lady day or Midsummer
which first happens after my decease Item I give to my Goddaughter Mrs
Eliz Glover daughter of my Cosin Toomes the yearly rent of tenne pounds
from my decease vnto the end of five years. Item to her brother Mr Rich
Toomes thirty pounds as a legacie Item I give to John Cullen sonne of
Tho Cullen deceased all what I have formerly given his father and more
one hundred pounds Item I will that what I have bequeathed to my Niece
Mary West be given to her husband my Cosin Rob West for his daughter
Amy West Item what should have bene to my Sister Dan deceased I will
be given my lo Niece her daughter in Law Item I give my Cosin Mrs Mary
Ranton fortie pounds to buy something to keep in remembrance of me
Item to my nephews Michaell and Will the sonnes of my brother Mich one
hundred pounds to either of them Item all the furniture of my chamber
and all the hangings I give to my godsonne Mr Eliab Harvey at his
marriage and all my red damaske furniture and plate to my Cosin Mary
Harvey Item I give my best velvet gowne to Doctor Scarbrowe.


Memorandum that upon Sunday the twentie eighth day of December in the
yeare of our Lord one thousand sixe hundred fiftie sixe I did againe
peruse my last will which formerly conteined three pages and hath
now this fourth page added to it. And I doe now this present Sunday
December 28 1656 publish and declare these foure pages whereof the
three last are written with my owne hand to be my last will In the
presence of Henneage Finch John Raby.

This will with the Codicill annexed was proved at London on the second
day of May In the yeare of our Lord God one Thousand six hundred fiftie
nine before the Judge for probate of wills and granting Adcons lawfully
authorised By the oath of Eliab Harvey the Brother and sole executor
therein named To whom Administracon of all and singular the goods
Chattells and debts of the said deceased was granted and committed He
being first sworne truely to administer.[62]

  CHAS. DYNELEY  } _Deputy_
  JOHN IGGULDEN  } _Registers._

  [62] [The will of Harvey is without date. But was almost certainly
  made some time in the course of 1652. He speaks of certain deeds of
  declaration bearing date the 10th of July, 1651; and he provides
  money for the completion of the buildings which he has “already begun
  to erect within the Colledge of Physicians.” Now these structures
  were finished in the early part of 1653. The will was, therefore,
  written between July 1651, and February 1653. The codicil is also
  undated: but we may presume that it was added shortly before Sunday
  the 28th of December 1656, the day on which Harvey reads over the
  whole document and formally declares and publishes it as his last
  will and testament in the presence of his friend Henneage Finch, and
  his faithful servant John Raby.]




  _Anastomosis_, 63, 127, 172
    how far observed by Harvey, 128
    Harvey states his views on, 179, 180

    pulsation of an, 15
    axillary, its bearing on the pulse, 30
    its effect on the pulse, 135

    importance of dissecting the lower, 42

    why its walls thicker than those of the pulmonary artery, 107
    case in which portion of, ossified, 137

  _Argent, Dr._
    dedication of treatise on Heart and Blood to, 5

    referred to, vii, 27
    on the pulse, 30
    on the chick, 34
    quoted in support of pulsation of heart of embryo, 46
    circular motion of rain suggested by, compared to that of the blood, 56
    on the heart, 93, 97, 105, 166
    his error regarding the mitral valve, 101
    on the study of the lower animals, 137
    on trusting to the senses, 160

    experiments of, 14, 28, 29, 129, 163
    outflow of blood in, 29

    ancient views regarding the, ix
    contain blood only, 12
    contain same blood as the veins, 12
    Galen’s experiment on, 12
    filled like bladders, not like bellows, 13
    dilation of, due to impulse of blood, 14
    diastole of, corresponds to systole of heart, 29
    called veins, by Galen, 30, and the ancients, 57
    why empty after death, 62, 140
    coronary, supply the heart itself, 88
    reason for greater thickness of coats of, 106
    nearer to heart, more they differ from veins, 106
    contained only aërial spirits, according to Erasistratus, 140

    ligature of an, of a snake, 66
    experiment of dividing an, 129, 146
    experiment on an exposed uncut, 136
    case of ossification of portion of an, 137

  _Arundel, Earl of_
    Harvey accompanied the, on an embassy to the Emperor, xxii

    discovered the lacteals, 117, 186
    lacteal vessels of, referred to by Harvey, 197


  _Baer, Von_
    Harvey, a precursor of, xxi

    on the arm to show flow of blood in the veins, 81 _et seq._

  _Bauhin, Caspar_
    his observations on the heart, 31

    of Harvey’s works, xxiv

    observations on the beat of the heart of a, 33
    observations on the heart of the chick, 34, 36

    its course from veins to arteries, 42
    in the lower animals, 43
    in the fœtus, 44
    its passage through the lungs, 48
    quantity of, passing through the heart, 55
    circular motion of the, 56
      demonstrated from impossibility of whole amount of, being derived
        from the ingesta, 58
    amount ejected from ventricle at each beat, 59
    enters a limb by arteries, leaves it by veins, 67
    circulation of, proved by experiments with ligatures, 67, 68
    quantity of, passing through bloodvessels supports circulation, 76
    circulation of, supported by valves in the veins, 78
    manner of escape of, in surgical operations, 107
    the whole of the, circulates, 114
    is cooled in passing through the lungs, 122
    force with which it flows from an artery, 136
    is of same nature in arteries and veins, 138, 143
      reasons why a different view has been held, 139, 140
    velocity of, varies in different parts, and at different times, 156
    gives heat to the heart, 167
    passage of, from arteries to veins, xvi, 168


  _Cæsalpinus, Andreas_
    claimed in Italy as the discoverer of the Circulation, xi
    this claim criticised, xii

  _Calidum innatum_, 145
    not distinct from the blood, 146

  _Canalis arteriosus_
    of fœtus, shrinks gradually after birth, 45

    too minute for Harvey to see, xvi
    first observed by Malpighi, xvi

  _Carotid artery_
    experiment on the, 129
    force with which blood flows from the, 136

  _Charles I._
    his interest in Harvey’s discovery, xviii
    Harvey appointed physician to, xxii
      remained such by request of the Parliament, xviii
    dedication to, of treatise on Motion of Heart and Blood, 3
    present at a demonstration by Harvey, 153

    first sign of the heart in the, 34
    Aristotle on, 34
    observations of, on the fourth and fifth days of incubation, 36

  _Chordæ tendineæ_, 99, 100

    absorbed by the blood, 92
    vessels containing, 186

  _Circulation of the Blood_
    circulation as distinct from motion, xii
    first suggested to Harvey’s mind, 56
    compared to circular movement of rain as suggested by Aristotle, 56
    confirmed by three propositions, 58
    varies in rapidity, 61
    explains the results of ligatures, 67 _et seq._
    explains phlebotomy, 73
    summary account of, 85, 168
    confirmed by probable reasons, 86
    proved by certain consequences, 90
    confirmed from structure of the heart in many different kinds of
      animals, 96
    doctrine of the, the opposite to that vulgarly entertained, 108
    first reply to Riolan on the, 111
    applies to the whole of the blood, 114
    in the mesentery, 119
    coronary, or a third and very short, 125
    through every part of the body, 126
    second reply to Riolan on the, 133
    reply to those who cry _cui bono?_, 149
    reasons given by opponents for not accepting the, 149, 150
    velocity of, varies with age, sex, temperament, etc., 156
    influenced by the emotions, 158
    recapitulation of work on Motion of Heart and Blood, 161
    interference with, followed by dangerous results, 171
    further illustrations of, 176 _et seq._

  _Columbus, Realdus_
    claimed as discoverer of the Circulation, xi
    referred to in relation to the Pulmonary Circulation, 12, 16, 50

  _Columnæ carneæ_
    of the heart, 99

    of disease spread, explained by circulation, 90
    nature of, referred to by Harvey, 193

    the source of all animal motion, 102
    of the fibres of the heart, 105
    of muscles as aid to movement of blood in the veins, 116

    means of acquiring, of physical truths discussed, 158

    vessels supply the heart with blood, 88
    circulation, a third, very short, 125
    vein usually has a valve at its orifice, 125


  _Darcy, Sir Robert_
    case of, illustrating obstruction of the circulation through the
      heart, 155

    supports Harvey’s discovery, xvii
    Harvey makes his acknowledgments to, 169
    his observations of the heart of a fish, 169
    his explanation of the pulse not accepted by Harvey, 170

  _Diastole and Systole_
    of arteries as of the heart, 138
    constituting the pulse, 163

    uses of, 112
    failed to reveal any of the “spirits” of the schoolmen, 141

    drinks, their quick action in illustration of the large quantity of
      blood circulating, 49

  _Ductus arteriosus_
    shrinks gradually after birth, 45
    its function in the fœtus, 98


    observations on the heart of the, 33

    Harvey a pioneer in the science of, xx

  _Ent, Dr. George_
    persuaded Harvey to publish his treatise on Generation, xx
    directed in Harvey’s will to present his books and collections to
      the College of Physicians, 216
    Harvey left him his presses and shelves, 216

    Harvey’s doctrine of, xxi

    thought the arteries contained only spirits or air, 40, 140

    the tides of, the motion of the heart as perplexing as, 22
    Galen refers to, in speaking of the use of the semilunar valves, 53
    Riolan applies, to the movement of the blood in the mesenteric
      vessels, 115

    importance of, for scientific observation, 160

    the direct appeal to, viii
    Galen’s, to show arteries contain only blood, 12
    Galen’s, to show arteries filled like bellows, controverted by
      Harvey, 14
    of arteriotomy, 14, 28, 29
    Galen’s, of dividing the trachea, 18
    to observe the beating heart, 24
    of dividing the gill vessels of fishes, 28
    on the hearts of an eel, a fish, and a pigeon, 33
    to show the capacity of the left ventricle, 59
    on the heart of a snake, 65
    of tying the veins below the heart in serpents and fishes, 65
    on a man’s arm with a bandage, 68
    on the veins of the arm by ligatures, 82, 84
    of tying the vena cava near the heart and dividing carotid artery, 129
    Galen’s, on an artery, 134
      performed and disproved by Harvey, 135
    on an exposed undivided artery, 136
    to show the blood of arteries and veins the same, 138
    to show the different character of outflow of blood from artery
      and vein, 147
    to show blood cannot pass from heart by the veins, 147
    with the dried intestine of a dog filled with water to illustrate
      the pulse, 152
    on the jugular vein of a fallow deer, 153
    by appeal to, endeavour to demonstrate circulation, 163
    of dividing exposed artery to observe effect on pulse, 163
    of tying the pulmonary veins, 165
    of bandaging arm and plunging it into cold water, 168
    of tying the vena portae, 171
    of tying the vena cava near the crural veins, 172
    on the body of a man recently hanged, to show course of blood
      through lungs, 177


  _Fabricius, Hieronymus_, of Aquapendente
    Harvey’s teacher of anatomy at Padua, xiv
    his views on the heart and lungs, 9
      pulmonary veins, 18
    his anatomical work, 23
    discovered the valves of the veins, 78

  _Finch, Heneage_
    Harvey’s cousin, advised him as to his will, 214
    witness to codicil of Harvey’s will, 217

    experiment on gill vessels of, 28
    observations on the heart of, 33
    the heart of, has only one ventricle, 42
    auricles of the heart of, 103

    Harvey refers to his visits to, 185, 194
      and three of his nephews, 199

    on Harvey’s work, viii

  _Foramen ovale_
    of heart of fœtus, 20, 44
    its significance in fœtal life, 47, 98

    Harvey’s treatise on the Heart and Blood first published there, xv

  _Fuliginous vapours_
    views of the ancients on, ix, 10, 11, 17


    high regard in which he was held by mediævalists, vii
    on the object of the pulse, 9
    his experiment to show arteries contain only blood, 12
    his experiment to prove arteries expand like bellows, and
      controverted by Harvey, 14
    his experiment of dividing the trachea of a dog, 18
    on the beat of the auricles, 32
    quotations from, on movement of the blood, 40, 41
    aware of the use of the semilunar valves, 51, 52
    believed blood passed from right ventricle into the lungs, 53
    on the structure of the heart, 105
    his experiment on an artery, 134
      performed and disproved by Harvey, 135

    at Padua with Harvey, vii, xiv
    as a pioneer in scientific discovery, viii

  _Generation of Animals_
    Harvey’s treatise on, its publication, xx
    interesting points in, xxi
    Harvey refers to his work on the, 177
    Quotation from, on the Acquisition of Knowledge, xix


    on Harvey’s discovery, xiii

    as a pioneer in scientific discovery, viii
    greatness of his discovery, viii, ix
    his life, xiii _et seq._
    his views on controversy, xviii, 133
    on the manner of acquiring knowledge, xix
    his treatise on Generation, xxi, 177
    his statue, xxii
    oration in his memory, xxii
    his brother Eliab, xxiii, 212, 219
    his various works, xxiv
    on the pursuit of truth, 7
    describes how his discovery was received, 23
    his letters, 175 _et seq._
    on the use of terms, 182
    his will, 212

    ideas about the, before the time of Harvey, ix
    object of its beat connected with Respiration by old anatomists, 9
    movements of the, 24
    contracts and becomes paler at its beat, 24, 25
    does not suck in the blood, 27
    the auricles and ventricles of the, their movements, 31
    the auricles of the, the primum vivens, ultimum moriens, 34
    observations on the heart of the chick, 34, 36
    always has auricles or something analogous, 35
    of a shrimp, its movements studied, 36
    movements of, summarised, 37
    intimate connection of lungs and, a grand cause of error to the old
      observers, 39
    of fish, has only one ventricle, 42
    great vessels of the, in the embryo, 44
    foramen ovale of the, in the fœtus, 44, 98, 165
    of embryo, pulsation, etc., known to Aristotle, 45
    compared figuratively to the sun, 57
    amount of blood ejected at each beat of the, 59
    of a live snake, observations on, 65
    influenced by emotions, 87
      curious case of distended heart under emotion, 156
    coronary vessels of, 88
    only organ containing blood for general use, 88
    structure of the, in different classes of animals confirms the
      circulation, 97
    papillary muscles and chordæ tendineæ of, 99
    arrangement and use of the valves of the, 100
    the heart a muscle and acts as such, so called by Hippocrates, 104
    development of the, in the fœtus, 104
    arrangement of the fibres of, 105
    the first part which exists, 105
    high importance of the, in the bodily economy, 105
    distension of, after hanging, 154
    Sir Robert Darcy’s case of ruptured, 155
    receives heat from the blood, 167
    innate heat of, suggested as cause of the pulse, 168
    of the fish, observations of motions of the, 169

    entitled the heart a muscle, 104
    his doctrine as to the constitution of the body, 142

    on the reception of Harvey’s discovery, xvii

  _Hofmann, Caspar_
    letter of Harvey to, 175

  _Horst, J. D._
    letters of Harvey to, 195, 197

  _Huxley, Prof. T. H._
    on Harvey’s treatise on Generation, xxi


  _Jugular vein_
    Experiment of dividing the, in the fallow deer, to show course of the
      contained blood, 153


  _King, The._ See _Charles I._


    discovered by Aselli, 117, 186
    Harvey refers to the researches of Aselli and Pecquet on the, 186
    Harvey discusses the, in a letter to R. Morison, 187, 188

  _Lamentius, Andreas_
    quoted by Harvey, 20, 22

  _Lennox, Duke of_
    Harvey accompanied him abroad, xxii

    of Harvey, 173 _et seq._

    of veins near the heart, 65
    assuming circulation, action and use of ligatures readily
      understood, 67, 68
    of vena cava, 129, 172
    of pulmonary veins, 165
    of vena portæ, 171

    absorbed food passes through the, 49
    absorbed chyle passes through the, 92
    in the fœtus, 92
    nature of blood brought to, 94
    chyle transferred to, by mesenteric vessels, 118

    speculation on changes in the blood passing through the, 48
    blood cooled on passing through the, 122, 145
    course of blood through the, shown by an experiment on the body of
      a man recently hanged, 177


    the first to observe the capillaries, xvi

  _Medical Observations_
    Harvey refers to his, 157, 158, 171

    externally applied confirm the circulation, 91

    bloodvessels of, 94, 115
    Harvey combats Riolan’s denial of circulation in vessels of the, 115
      Harvey suggests an experiment to convince him, 171
    valves in the mesenteric veins, 116
    veins of, transfer chyle to the liver, 118

    doctrine of, contrasted with that of Epigenesis, xxi

  _Mitral Valve_
    references to, 17, 101
    Aristotle’s error regarding the, 101

  _Morison, R._
    letter of Harvey to, 185

    of the heart, 24, 36
    of the auricles and ventricles, 31
    of the heart summarised, 37
    of the blood from veins to arteries, 42
    of the blood in the fœtus, 44
      lower animals, 43
      is circular, 58
    of the blood in the veins aided by the circumjacent muscles, 116

    the heart a, and so called by Hippocrates, 104


  _Nardi, John_, of Florence
    letters of Harvey to, 184, 193, 199

  _Nutrition_ of the Tissues
    connection of the, with the circulation, 119


  _Oration, Harveian_
    founded by Harvey, delivered annually at the College of
      Physicians, xxii


    Harvey and Galileo there together, vii, xiv
    famous for its university, xiv
    Harvey studies medicine at, xiv

  _Parr, Thomas_
    anatomical examination of the body of, 207

    how best advanced, 112

    Harvey refers to his discovery of the Receptaculum Chyli, 186
    Harvey praises his industry, 196
      See also _Lacteals_

    explained by the circulation, 73
    shows nature of flow of blood in the veins, 154
    influenced by temperature and mental state, 157

  _Physicians, College of_
    Harvey elected a Fellow of the, xv
    Harvey built a Convocation Hall for, and gave books to, xvii
      his treatise dedicated to President and Fellows of, 5

    importance of its study, 112

    action of, confirmatory of the circulation, 90

  _Pulmonary Artery_
    formerly supposed to carry nourishment to lungs, 17
    why coats of, thinner than those of aorta, 107
    transmits far more blood than required for nutrition, 108

  _Pulmonary Circulation_
    speculation as to its use, 48
    follows from continual passage of blood from right ventricle to
      lungs, and from lungs to left ventricle, 54
    course of, shown in body of a man recently hanged, 177

  _Pulmonary Veins_
    ancient views regarding their function, 17

    caused by contraction of the ventricle, 29
    due to the impulse or shock of the blood, 30
    Aristotle on the, 30
    found in all parts of the body, 121
    not inherent in walls of arteries, 135
    in an artery beyond an aneurism, 135
    in an artery beyond an ossified portion, 137
    illustrated by experiment with dried intestine of a dog, 152
    cause of, in arteries near the heart, 163


    how confirmatory of the circulation, 90

  _Riolan, John, Jun._
    controversy with Harvey, xix
    quoted on the movements of the heart, 31
    Harvey’s First Disquisition addressed to, 109
    presented a copy of his work to Harvey, 111
    his views on the circulation, 113
    denies the mesenteric circulation, 115
    favoured view that septum of heart is permeable, 123
    Harvey’s Second Disquisition to, 131


  _Scarborough, Dr._
    a friend to whom Harvey left his surgical instruments, 216
      and his velvet gown, 218
    directed by Harvey’s will to present to College of Physicians his
      books and collections, 216

    dependent on pre-existing knowledge of more obvious things, 160

  _Semilunar Valves_
    references to, 16, 45
    Galen aware of their use, 51
    function to prevent regurgitation, 116, 153

    facts cognisable by, wait on no opinion, 150
    importance of appealing to the, 158, 159
    Aristotle on trusting to the, 160

  _Septum of the Heart_
    Cæsalpinus thought it permeable, xii
    Harvey on the view that it is porous, 19, 20
    Riolan believed it porous, 123

  _Servetus, Michael_
    gave a description of the pulmonary circulation, x
    curious history of his work containing it, xi

    movements of the heart of a, 36

  _Sigmoid Valves_
    See _Semilunar_

  _Silvius, Jacobus_
    discovered the valves of the veins according to Riolan, 78

  _Simon, Sir John_
    on Harvey’s discovery, ix

  _Slegel, P. M._
    letter of Harvey to, 176

    observations of heart and bloodvessels of a live, 65

    views of the ancients regarding, ix
    arteries supposed to contain, by Erasistratus, 140
    the common subterfuge of ignorance, 141
    three kinds of, admitted by the medical schools, 141
    not distinct from the blood, 143, 146

    bloodvessels connected with the, 94
    vein of, has a valve, 116

  _Systole and Diastole_
    of arteries as of heart, 138
    constitute the pulse, 163
    observations on, 170


  _Transmission of Disease_
    discussed, 193

  _Tricuspid Valve_
    referred to, 16, 101, 153


  _Umbilical Vein_
    function of, 118


    semilunar, 16, 45, 116, 153
    tricuspid, 16, 101, 153
    mitral, 17
    Galen on valve of pulmonary artery, 51
    of the veins discovered by Fabricius or Silvius, 78
    of veins, their structure, arrangement, and use of, 78, 80
    Fabricius did not understand use of valves of veins, 79
    of veins compared with sigmoid valves, 82
    experiments on the arm to show action of the, and how the blood
      moves in the veins, 82, 84
    not found in all veins, 116
    of the mesenteric veins, 116
    coronary vein has a valve at its orifice, 125

    pulmonary, ancient views regarding their position, 17
    near the heart, experiment of ligaturing the, 65
    of the arm, experiment on with bandages, 82, 84
    coronary, 88
    of the mesentery, the function of the, 118
    umbilical, function of, 118
    coronary vein has a valve at its orifice, 125
    experiment on, by cooling the arm, 168
    valves of the. See _Valves_

  _Vena cava_
    of snake, experiment upon the, 65
    experiment of tying, near the heart, 129

  _Vena portæ_
    blood passes from the, through the liver, 118
    its branches, 128
    Harvey suggests the experiment of ligaturing it, 171

    no right ventricle if no lung, 15, 54
    the left, the principal part of the heart, 98
    the left, three times thicker than the right, 100
    case of rupture of the, 155

    structure of both, almost identical, 15
    both contract simultaneously, 19
    movements and use of the, 37
    in the fœtal heart, 98
    valves of the, 100

    the “Father of Anatomy”, x
    Professor of Anatomy at Padua, xiv
    did not properly understand the heart’s motion, 26
    refers to Galen’s experiment on an artery, 135
    wrong in his interpretation of Galen’s experiment, 138

  _Vlackveld, John_
    letter of Harvey to, 200


    felt in the hand on loosening bandage on the arm, 69
    restored to parts chilled by the influx of blood, 121, 146

    of Harvey drawn up by Heneage Finch, 212, 214
    proved by Eliab Harvey, 219
    legacies by, to Drs. Scarborough and Ent, 216

  _Wolff, Caspar_
    Harvey as forerunner of, xxi

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