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THE CIRCULATION OF THE BLOOD
THE CIRCULATION OF THE BLOOD THOMAS H. HUXLEY [*footnote] A Lecture delivered in the Free Trade Hall November 2nd
1878.
I DESIRE this evening to give you some account of the life and labours
of a very noble Englishman--William Harvey.
William Harvey was born in the year 1578 and as he lived until the year
1657 he very nearly attained the age of 80. He was the son of a small
landowner in Kent who was sufficiently wealthy to send this his
eldest son to the University of Cambridge; while he embarked the
others in mercantile pursuits in which they all as time passed on
attained riches.
William Harvey after pursuing his education at Cambridge and taking
his degree there thought it was advisable--and justly thought so in
the then state of University education--to proceed to Italy which at
that time was one of the great centres of intellectual activity in
Europe as all friends of freedom hope it will become again sooner or
later. In those days the University of Padua had a great renown; and
Harvey went there and studied under a man who was then very
famous--Fabricius of Aquapendente. On his return to England Harvey
became a member of the College of Physicians in London and entered
into practice; and I suppose as an indispensable step thereto
proceeded to marry. He very soon became one of the most eminent
members of the profession in London; and about the year 1616 he was
elected by the College of Physicians their Professor of Anatomy. It
was while Harvey held this office that he made public that great
discovery of the circulation of the blood and the movements of the
heart the nature of which I shall endeavour by-and-by to explain to you
at length. Shortly afterwards Charles the First having succeeded to
the throne in 1625 Harvey became one of the king's physicians; and it
is much to the credit of the unfortunate monarch--who whatever his
faults may have been was one of the few English monarchs who have shown
a taste for art and science--that Harvey became his attached and
devoted friend as well as servant; and that the king on the other
hand did all he could to advance Harvey's investigations. But as you
know evil times came on; and Harvey after the fortunes of his royal
master were broken being then a man of somewhat advanced years--over
60 years of age in fact--retired to the society of his brothers in and
near London and among them pursued his studies until the day of his
death. Harvey's career is a life which offers no salient points of
interest to the biographer. It was a life devoted to study and
investigation; and it was a life the devotion of which was amply
rewarded as I shall have occasion to point out to you by its results.
Harvey by the diversity the variety and the thoroughness of his
investigations was enabled to give an entirely new direction to at
least two branches--and two of the most important branches--of what
now-a-days we call Biological Science. On the one hand he founded all
our modern physiology by the discovery of the exact nature of the
motions of the heart and of the course in which the blood is propelled
through the body; and on the other he laid the foundation of that
study of development which has been so much advanced of late years and
which constitutes one of the great pillars of the doctrine of evolution.
This doctrine I need hardly tell you is now tending to revolutionise
our conceptions of the origin of living things exactly in the same way
as Harvey's discovery of the circulation in the seventeeth century
revolutionised the conceptions which men had previously entertained with
regard to physiological processes.
It would I regret be quite impossible for me to attempt in the course
of the time I can presume to hold you here to unfold the history of
more than one of these great investigations of Harvey. I call them
"great investigations" as distinguished from "large publications." I
have in my hand a little book which those of you who are at a great
distance may have some difficulty in seeing and which I value very
much. It is I am afraid sadly thumbed and scratched with annotations
by a very humble successor and follower of Harvey. This little book is
the edition of 1651 of the 'Exercitationes de Generatione'; and if you
were to add another little book printed in the same small type and
about one-seventh of the thickness you would have the sum total of the
printed matter which Harvey contributed to our literature. And yet in
that sum total was contained I may say the materials of two
revolutions in as many of the main branches of biological science. If
Harvey's published labours can be condensed into so small a compass
you must recollect that it is not because he did not do a great deal
more. We know very well that he did accumulate a very considerable
number of observations on the most varied topics of medicine surgery
and natural history. But as I mentioned to you just now Harvey for
a time took the royal side in the domestic quarrel of the Great
Rebellion as it is called; and the Parliament not unnaturally
resenting that action of his sent soldiers to seize his papers. And
while I imagine they found nothing treasonable among those papers yet
in the process of rummaging through them they destroyed all the
materials which Harvey had spent a laborious life in accumulating; and
hence it is that the man's work and labours are represented by so
little in apparent bulk.
What I chiefly propose to do to-night is to lay before you an account of
the nature of the discovery which Harvey made and which is termed the
Discovery of the Circulation of the Blood. And I desire also with
some particularity to draw your attention to the methods by which that
discovery was achieved; for in both these respects I think there will
be much matter for profitable reflection.
Let me point out to you in the first place with respect to this
important matter of the movements of the heart and the course of the
blood in the body that there is a certain amount of knowledge which
must have been obtained without men taking the trouble to seek
it--knowledge which must have been taken in in the course of time by
everybody who followed the trade of a butcher and still more so by
those people who in ancient times professed to divine the course of
future events from the entrails of animals. It is quite obvious to
all from ordinary accidents that the bodies of all the higher animals
contain a hot red fluid--the blood. Everybody can see upon the surface
of some part of the skin underneath that skin pulsating tubes which
we know as the arteries. Everybody can see under the surface of the
skin more delicate and softer looking tubes which do not pulsate which
are of a bluish colour and are termed the veins. And every person who
has seen a recently killed animal opened knows that these two kinds of
tubes to which I have just referred are connected with an apparatus
which is placed in the chest which apparatus in recently killed
animals is still pulsating. And you know that in yourselves you can
feel the pulsation of this organ the heart between the fifth and
sixth ribs. I take it that this much of anatomy and physiology has
been known from the oldest times not only as a matter of curiosity
but because one of the great objects of men from their earliest
recorded existence has been to kill one another and it was a matter
of considerable importance to know which was the best place for hitting
an enemy. I can refer you to very ancient records for most precise and
clear information that one of the best places is to smite him between
the fifth and sixth ribs. Now that is a very good piece of regional
anatomy for that is the place where the heart strikes in its
pulsations and the use of smiting there is that you go straight to the
heart. Well all that must have been known from time immemorial--at
least for 4000 or 5000 years before the commencement of our
era--because we know that for as great a period as that the Egyptians
at any rate whatever may have been the case with other people were in
the enjoyment of a highly developed civilisation. But of what
knowledge they may have possessed beyond this we know nothing; and in
tracing back the springs of the origin of everything that we call
"modern science" (which is not merely knowing but knowing
systematically and with the intention and endeavour to find out the
causal connection of things)--I say that when we trace back the
different lines of all the modern sciences we come at length to one
epoch and to one country--the epoch being about the fourth and fifth
centuries before Christ and the country being ancient Greece. It is
there that we find the commencement and the root of every branch of
physical science and of scientific method. If we go back to that time
we have in the works attributed to Aristotle who flourished between
300 and 400 years before Christ a sort of encyclopaedia of the
scientific knowledge of that day--and a very marvellous collection of
in many respects accurate and precise knowledge it is. But so far as
regards this particular topic Aristotle it must be confessed has not
got very far beyond common knowledge. He knows a little about the
structure of the heart. I do not think that his knowledge is so
inaccurate as many people fancy but it does not amount to much. A very
few years after his time however there was a Greek philosopher
Erasistratus who lived about three hundred years before Christ and
who must have pursued anatomy with much care for he made the important
discovery that there are membranous flaps which are now called
"valves" at the origins of the great vessels; and that there are
certain other valves in the interior of the heart itself.
Fig. 1.--The apparatus of the circulation as at present known. The
capillary vessels which connect the arteries and veins are omitted
on account of their small size. The shading of the "venous system" is
given to all the vessels which contain venous blood; that of the
"arterial system" to all the vessels which contain arterial blood.
I have here (Fig. 1) a purposely rough but so far as it goes
accurate diagram of the structure of the heart and the course of the
blood. The heart is supposed to be divided into two portions. It
would be possible by very careful dissection to split the heart down
the middle of a partition or so-called 'septum' which exists in it
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