LECTURE 
ON THE 
PHYSIOLOGY OF THE HEART, 
And its Connections with the Brain, 
DELIVERED AT A MEETING AT THE SORBONNE, THE 27tii 
MARCH, 1865, 
BY CLAIJDE BERNARD, 
Member of the Institute of France, of the Imperial Academy of Med- 
icine at Paris, of the Royal Society of London; Professor of 
the College of France and the Sorbonne. 
TRANSLATED BY 
J. S. MOREL, M. D., SAVANNAH, GA. 
SAVANNAH: 
PURSE & SON. 
1867. TABLE OF FIGURES. 
FIGURE 1.—Longitudinal section of the human heart, showing 
its four cavities, ° 12 
FIGURE 2.—Diagram intended to illustrate the mechanism of the 
circulation, 14 
FIGURE 3.—Longitudinal section of the human heart, to show the 
mechanism of the circulation in its four cavities, . . 17 
FIGURE 4.—Cardiographic or Sphygmographic Apparatus of Mr. 
Marey, for directly inscribing the pulsations of the heart, . 20 
FIGURE 5.—Tracing of the pulsations of the heart of a young man 
in the normal state, . 22 
FIGURE G.—Tracing of the pulsations of the heart of a rabbit, . 22 
FIGLTRE 7.—Tracing of the pulsations of the heart of a frog, . 23 
FIGURE 8.—Tracing of the pulsations of the heart of an eel, . 23 
FIGURE 9.—Tracing of the pulsations of the heart of a tortoise, 24 
FIGURE 10.—Tracing of the pulsations of the heart of a crab, . 24 
FIGURE 11.—Area vasculosa, or germinative field, representing the 
primitive circulation of the chick in the egg, . . . . 2G 
FIGURE 12,—Successive periods in the development of the heart 
of the chicken, 28 
FIGURE 13.—The heart with the nervous branches which it re- 
ceives from the brain, 31 
FIGURE 14.—Tracing representing the beating of the heart of the 
horse, to show the paralysing influence which irritation of the 
pneumogastric nerve exercises over the contractions of the heart, 33 
FIGURE 15.—Tracing representing the contractions of the muscles 
of the foot of a frog, to show that the irritation of the nerves 
provoke these contractions, 33 
FIGURE 16.—Anatomical connections of the heart to the brain, 
by the carotid arteries and the pneumogastric nerves, to explain 
the reactions of these two organs on each other, . . .44 ERRATA. 
Page 15, 20th line—for realised, read realized. 
Page 28, 10th line—for bulba, read bulb. 
Page 32, 23d line—for entrance towards, read commencement of. 
Page 33, 3d line in the description of Fig. 14—semi-colon (;) after 
pneumogastric. 
Page 34, lGtli line—semi-colon (;) after arrested. 
Page 45, 6th line—comma (,) after souvenir. 
In the description of the 2d Plate, higher should read lighter. On the Physiology of the Heart ami its Con- 
nections with the Brain. 
Gentlemen : 
I intend to entertain you in a general manner with 
the physiology of the heart, hut will dwell more particu- 
larly upon those points which sefcm necessary to clear 
up the physiology of the heart of man. 
To the physiologist the heart is the central organ of 
the circulation of the blood, and in this respect it is an 
organ essential to life. But by a singular privilege, en- 
joyed by no other organic apparatus, the word heart has 
passed, like the ideas one has of its functions, with very 
different acceptations, from the language of the physi- 
ologist into the language of the poet, the romancer and 
the man of the world. The heart may not only be a 
vital motor apparatus, pumping the sanguineous liquid 
into every part of our body, which it animates, it may 
also be the seat and symbol of the noblest and ten- 
derest sentiments of our soul. The study of the human 
heart may be pursued not only by the physiologist, it 
may also serve as the basis of the conceptions of the phi- 
losopher and the inspirations of the poet and the artist. 
The question now before us concerns the anatomical 
heart—that is to saj, the heart studied from a physio- 
logical, scientific, and purely experimental point of view. 10 
ON THE MY3IOLOGY OF THE IIEAlit 
But will this rapid examination which we are about to 
make of the functions of the heart overthrow the ideas 
generally entertained respecting it ? Ought physiology 
to dissipate the illusions, and show us that the senti- 
mental role at all times attributed to the heart, is but 
a fiction purely arbitrary ? In a word, shall we be 
obliged to acknowledge a complete and peremptory con- 
tradiction between science and art, between sentiment 
and reason ? As to myself, I do not believe in the pos- 
sibility of that contradiction. Truth cannot differ from 
itself, and the truth of the man of science will not be 
contradicted by the truth of the artist. I believe, on 
the contrary, that the science which Hows from a pure 
source will become luminous to all, and that science and 
art should give their aid in explaining and interpreting 
for each other. I think, indeed, that in its elevated 
regions, human knowledge forms an atmosphere com- 
mon to all cultivated intelligences, in which the man of 
the world, the artist and the savant, will, as a matter of 
course, meet and fully comprehend each other. 
In that which follows, I will not attempt to deny, in 
the name of science, all that may be said, in the name 
of art, upon the heart considered as an organ intended 
to express our affections and sentiments. On the con- 
trary, I would like to be able to confirm art by science, 
in trying to explain, by means of physiology, that 
which, until now, has been but a simple intuition of the 
mind. I know that I have undertaken a very difficult 
task, it may be one of temerity, because of the slight 
advance that is yet made in the science of the pheno- 
mena of life. However, the beauty of the subject, and 
the light that physiology already seems to shed upon it, 
determine and encourage me to the investigation. Be- AND ITS CONNECTIONS WITH THE BRAIN. 
11 
sides, in speaking here upon the physiology of the heart, 
it will not be necessary to go into the details of a com- 
plete experimental and analytical investigation ; at this 
time, this would be impossible—it is only a simple test 
that I wish to make, and it will suffice me in express- 
ing my physiological ideas to support them by the 
clearest and best ascertained facts in science. 
The heart is truly a living motor machine, a forcing 
pump, intended to distribute to all of the organs of 
our body the nutritious fluid, the excitor of their 
functions. This mechanical role characterises the heart 
in an absolute manner, and wherever the heart exists, 
however simple it may be, or whatever complication it 
may present in the animal series, it constantly and ne- 
cessarily performs this function of organic irrigator. 
The anatomist regards the human heart as a viscus, 
that is, as one of the organs which forms a part of the 
apparatus of nutrition, situated in the splanchnic cavities. 
Everyone knows that the heart is placed in the tho- 
rax between the lungs—that it has the form of a cone, 
whose base is fixed by large blood vessels; whose point 
is free, inclining downwards to the left, in such a way as 
to place it between the fifth and sixth ribs below the left 
nipple. As to the nature of its tissue, the heart belongs 
to the muscular system; it is divided into cavities, 
which arc reservoirs for the blood—this is the reason 
why anatomists still' call it a hollow muscle. In the 
human heart are four compartments or cavities; two 
form the superior part, or the base of the heart, and are 
called the auricles—they receive the blood from all parts 
of the body, by means of large tubes, called veins; the 
other cavities form the lower portion, or apex of the 
heart; they are the ventricles, and are intended to force 12 
ON T11E PHYSIOLOGY OF THE HEART 
the blood into all parts of the body, by means of large 
vessels, called arteries (Fig. 1). 
Fig. i.—Longitudinal section of the heart of man, showing its four 
cavities. 
od.—Right auricle, vd.—Right ventricle, or/.—Left auricle. tvg.—Left ven- 
tricle. The arrows placed at the entrance of the different vessels ter* 
ininating at the cavities of the heart, indicate the direction of the 
current of the blood in these vessels. 
Each auricle communicates with the ventricle which 
is below it on the same side, but a longitudinal septum 
separates laterally the auricles and ventricles in such a 
way, that the human heart, which is really double, is 
divided into two simple hearts, each formed of one auri- 
cle and one ventricle, situated, one on the right and the 
other on the left of the middle septum. Each ventricu- 
lar cavity is furnished with two valves. The one placed AND ITS CONNECTIONS WITH THE BE AIN. 
13 
where the blood passes from the auricle to the ventricle, 
is called the ouriculo ventricular valve ; the other, situated 
where the blood leaves the ventricle by the artery, is 
called the sigmoid valve. 
The human heart, as Avell as that of mammals and 
birds, is anatomically, double, and composed of two sin- 
gle hearts, called the right heart and the left heart. Each 
of these hearts play a very different part in the economy 
(Fig. 2). The left heart, called the heart of red blood, 
is destined to receive into its auricle, by the pulmonary 
veins, the pure and lively red blood which comes from 
the lungs; this blood passes into its ventricle, which 
distributes it by the arteries to every part of the body, 
where it becomes impure and black. The right heart, 
called the heart of black blood, receives into its auricle, 
by the vena cava, the impure blood which comes from 
every part of the body, and passes it afterwards into its 
ventricle, to be distributed to the lungs, where it becomes 
pure and of a lively red color. In a word, the left heart 
presides over the distribution of the vital liquid to all of 
our organs, and to all of our tissues; and the right heart 
presides over the revivification of the blood in the 
lungs, to restore it to the left heart. 
These premises being established, we shall consider 
the heart as an organ distributing life to all parts of our 
body, sending to them the nutritious liquid which is 
indispensible to their life, and the manifestation of their 
functions. As to the nutritious liquid itself, it is repre- 
sented by the blood, which is identical in all vertebrated 
animals, whatever may be their diversity in the animal 
species, and the variety of their food. 
In the external phenomenon of the mode of feeding, 
the zoologist distinguishes the ferocious carnivora, which 14 
ON THE PHYSIOLOGY OF TIIE HEART 
Fig. 2—Intended to explain the mechanism of the circulation 
o.—Left auricle, vg.—Left ventricle, o.—right auricle, vd.—Right ven- 
tricle. The circulating system of red blood consists of arteries, over 
which the left heart presides—oog. is represented by the higher portion 
of the figure. The circulating system of dark blood consists of the veins 
over wldch the right heart presides—ood. is represented by the greyish 
tint. The arrows indicate the direction of the current of the different 
vessels. Above fcnd below are seen the capillary network of the supe- 
rior and inferior portions of the body, where the arterial blood is trans- 
formed into venous blood, and in the middle, the capillary network of 
the lungs, where the venous blood is revivified, to become arterial. And its connections with the brain. 
15 
feed upon palpitating flesh, the peaceful ruminant, 
which lives upon the herbs of the field, the frugivora 
and gramenivora, which are nourished more particularly 
by fruits and grain ; but when we descend into the inti- 
mate phenomenon of nutrition, general physiology 
teaches us that that which, properly speaking, is nour- 
ished in animals, is not the specific and individual type, 
which varies to infinity, but the elementary organs and 
tissues only, which are everywhere destroyed and live in 
the same manner. According to Goethe, nature is a 
great artist. Animals are constituted of the same or- 
ganic materials; it is the arrangement and relative dis- 
position of these materials which determine the variety 
of forms and the specific animal properties of these 
truly organised monuments. In like manner in the 
monuments of men, the materials are alike in all of their 
physical properties, and however different their arrange- 
ment, the various ideas may be realized, and give rise 
either to a palace or a cottage. In one word, the spe- 
cific type exists, but only in the state of an idea realised. 
Physiologically, it is not the animal type which lives 
and dies, but the organic materials or tissues which 
compose it; in the same way with the edifice which de- 
cays, it is not the ideal type of the monument which 
deteriorates, but only the stones of which it is built. 
We cannot, then, deduce from general physiology any 
essential difference in the organic nutrition, from the 
great variety of the food of animals. In man and all 
other animals, the elementary organs and living tissues 
are sanguinary; that is to say, they feed upon the blood 
in which they are immersed. They live there, as aquatic 
animals live in water, and in the same way that it be- 
comes necessary to renew the water which changes and 16 
ON TIIF. niYSIOLOOV OF THE HEART 
loses its nutritive elements, so it becomes necessary to 
renew, by means of tlie circulation, the blood which 
loses its oxygen and is charged with carbonic acid gas. 
This, then, is precisely the duty devolving upon the heart. 
The system of the left heart carries the blood to the 
organs which animate them ; and the system of the right 
heart carries away the blood which has given them mo- 
mentary life. When we wish to understand the func- 
tions of an organ physiologically, it is always necessary 
to trace the vital properties of the substance of which it 
is 'Composed to their origin—it is consequently in the 
properties of the tissue of the heart that we will be able 
to find the explanation of its functions. No difficulty 
will be experienced in making this investigation, for as 
we have already said, the heart is a muscle possessing all 
of the physiological properties of that tissue. It will suf- 
fice, then, to call to your notice that this fleshy or mus- 
cular tissue consists of fibres which possess the property 
of contracting. 
When the muscular fibres are disposed so as to form a 
long muscle, whose extremities are inserted into two 
bones, forming a joint, the necessary effect of the con- 
traction or shortening of the fibre is to cause the two 
bones to move on each other, thus approximating; but 
when the muscular fibres are disposed so as to constitute 
the walls of a muscular pouch, as is the case in the 
heart, the necessary effect of the contraction of the mus- 
cular tissue is to shut up or to cause the cavity to dis- 
appear more or less completely, by expelling its contents. 
This enables us to understand how the blood is expelled 
in a direction determined by the disposition of the 
cardiac valves at each contraction of the cavities of the 
heart (Fig. 3). AND ITS CONNECTIONS WITH THE BRAIN. 
Fig. 3.—Longitudinal section of the heart of man, to show the mech 
anism of the circulation in the different cavities. 
od.—Right auricle, vd.—Right ventricle, ot7.—Left auricle, vg.—Left ven- 
tricle. The arrows placed at the opening of the different vessels ter- 
minating at the cavities of the heart, indicate the current of the 
blood in these vessels. 
When the auricle contracts, the blood is sent into the 
ventricle, because the auriculo ventricular valve is re- 
laxed ; when the ventricle contracts, the blood is sent 
into the arteries, because the sigmoid, or arterial valves, 
arc relaxed, to-allow the blood to pass at the same time 
that the auriculo ventricular valve contracts, to prevent 
the blood from flowing back into the auricle. The con- 
traction of the cavities of the heart which empties them 
is followed by a dilatation, during which they are again 
filled with blood, then by a new contraction which again 
empties them, and thus the circle is continued. It 18 
ON THE PHYSIOLOGY OF T1IE HEART 
follows, that the motion of the heart consists of a succes- 
sion of alternate movements of contraction and dilata- 
tion of these cavities. The contractile movement is 
called the systole; the diastole is the act of dilatation. 
The four cavities of the heart contract and dilate succes- 
sively, two and two, first, the two auricles, then the two 
ventricles. A very short interval of repose separates 
the contraction of the auricles from the contraction of 
the ventricles ; a little longer interval then succeeds the 
contraction of the ventricles. It would be entirely for- 
eign to our subject to describe, in detail, the mechanism 
of the circulation in the different cavities of the heart. 
In our explanations further on, wo shall have to take 
notice only of the function of the left ventricle, which, 
as we have -already said, is the ventricle that supports, 
feeds and animates all the organs of the body. It will 
suffice us, then, to say, .that at the moment of the con- 
traction of this ventricle, the heart projects itself for- 
ward and strikes, like the beating of a clock, between 
the fifth and sixth ribs, below the left breast. This is 
called the beating of the heart. At the same moment of 
the contraction of the left ventricle, the blood is sent 
into the aorta, and by this channel, into all of the arte- 
ries of the body, with a pressure capable of supporting 
a oolumn of mercury of about five inches in height. It 
is that which produces the disturbance observed in all 
of the arteries, and which is called the .pulse. 
All of the mechanical movements of the heart have 
been the object of laborious investigation, and modern 
science has studied the phenomena of the circulation by 
the aid of graphic processes, which give to these re- 
searches great exactness. The only point to which we 
will call your attention, is that the heart is a true living 19 
AND ITS CONNECTIONS WITH THE BRAIN. 
machine, which acts like a forcing pump, in which the 
piston is replaced by the muscular contraction. The 
heart itself can trace upon paper each of its contractions 
with their slightest modifications, and it may then he 
said, without metaphor, that we read the human heart. 
Dr. Marey, to whom the Academy of Sciences has 
ordered a premium, this year, for his important works 
on the circulation of the blood, will give you an idea of 
these graphic means, by exhibiting before you experi- 
ments with the apparatus which he has invented, or 
brought to its present perfection (Fig. 4). 
The cardiographic apparatus for the examination of 
the human heart, is composed of two parts—a stethc- 
scopic drum (A), intended to detect the beatings of the 
heart, and a registry drum (B), intended to write them 
off. The stethescopic drum (A) intended to receive the 
impulses, should be applied overlie region of the heart; 
it is formed by a funnel, the broad portion of which is 
exactly closed by two membranes of caoutchouc (/, /,) 
betwcecn which, water is introduced, so as to make 
them swell out in the form of a double convex. The 
registering drum (B) is formed by another funnel, the 
broadest part of which is closed by a single membrane 
of caoutchouc, on which rests a small lever (L), as light 
as a feather; these two funnels are connected by a tube 
of caoutchouc (C), which transmits the vibrations of the 
receiving'drum (A) to the curegistcring drum (B). Each 
pulsation of the heart reverberates against the water 
drum of the stethescopic funnel; the air behind these 
distended membranes vibrates—these vibrations arc 
transmitted by means of the air which fills the caout- 
chouc tube, to the membrane of the registering drum, 
which, vibrating in its turn, causes the little lever to 20 
OST THE PHYSIOLOGY OF THE HEART 
Fig. 4.—Cardiographic or Sphygmograpliic Apparatus of Mr. Marer, for 
directly inscribing the pulsations of the heart. 
A. Stethescopic drum, which is placed on the chest, to detect the beatings 
of the heart. ir i. Two Membranes of caoutchouc, protruding in opposite 
directions and having between them a lenticular cavity filled with water. 
B. Registering drum, covered by a caoutchouc membrane slightly protru- 
ding h, on which is a small prism, which supports the lever L. C. Caout- 
chouc tube, intended to transmit the vibrations of the receiving drum A, 
to the registering drum B. c. Valve, for regulating the quantity of air 
contained in the caoutchouc tube C. L. A very light lever, jointed at one 
of its extremities so as to move freely around in a vertical plane ; it rests 
upon a small prism, fixed to the caoutchouc membrane A, of the register- 
ing membrane B, and is raised or lowered with it; its free extremity rests 
against the blackened paper ab: nb. Blackened tablet, moving regularly 
on a railway from b to «, and which receives the inscriptions of the mo- 
tions of the lever L, representing the beatings of the, heart. 
move; its point writes, upon tlie moving paper, black- 
ened with lamp-black, the pulsations of the heart. In 
this way is traced a figure written by'the heart itself, 
and which permits us to read its most intimate func- 
tions. The cardiograph is an instrument so much the 
more delicate and correct as it can be more closely 
applied over the heart, and as it is the least separated 
by the walls of the chest. Without explanation, it AND ITS CONNECTIONS WITH THE BRAIN. 
21 
will readily appear, why it is more easy to read the 
heart of children than that of adults, and why, also, 
it is naturally more difficult to read the heart of women 
than that of men. 
It is not my intention to initiate you into the interpre- 
tation of all of the cardiac writings in the normal and 
pathological state : I wish simply to exhibit to you a 
few tracings representing the beatings of the heart either 
in man or different animals, so as to give you an exact 
idea of what may he obtained by these graphic means. 
Here is traced the beatings or pulsations of the heart 
of a young man in the natural or normal state (Fig. 5). 
Here is traced the pulsations of the heart of a rabbit 
(Fig. 0). 
If we pass on now to cold-blooded animals, whose 
hearts are simple, we will see the tracings of the pul- 
sations also simplified in a corresp<®ding manner.* 
* To obtain a tracing of cold-blooded animals, the cardiographic instru- 
ment. is simplified: it consists simply of an enregistering lerer, which rests 
directly over the heart of the animal. ON THE PHYSIOLOGY OF THE HEART 
A. Systole of the auricle. B. Beginning of the systole of the ventricle. C. End of the systole of the ven- 
tricle. D. Particular motion, due, perhaps, to the sudden arrest of the blood in the ventricle during its 
relaxation. 
Fig. 5—Tracings of the pulsations of the heart of a young man in the normal state. 
Fig. G.—Tracings of the pulsation of the heart of a rabbit. AND ITS CONNECTIONS WITH THE BRAIN. 
The tracing of the pulsations of the heart of a frog 
(Fif. 7). 
Fit;. 7.—Tracings of the pulsations of the heart of a frog. 
Fn:. S.—Tracings of the pulsation of the heart of an eel. 
A. Systole of the auricle. B. Systole of the ventricle. 
A. Svstolo of the auricle. B. Systole of the ventricle. 
The tracing of the heart of an eel (Fig. 8). ON THE PHYSIOLOGY OF THE HEART 
The tracing of the heart of a tortoise (Fig. 9). 
Fig. 9.—Tracings of the pulsations of the heart of a loitoise. 
Fig. 10.—Tracings of the pulsations of the heait ( f a crab. 
A. Systole of the aurie’e. It. C. S.sto'c of the ventriel*. 
Lastly, is the tracing of the beatings of the heart of 
an invertebrate animal, a crab (Fig. 10). AND ITS CONNECTIONS WITH THE BRAIN. 
25 
question which we now wish to examine more 
particularly in this lecture, is how the heart, that simple 
motor of the circulation of the blood, can, by re-acting 
under the influence of the nervous system, co-operate 
with that exceedingly delicate mechanism of the senti- 
ments which are produced in us. 
The heart strikes us at once, as a strange organ, on 
account of its exceptional activity. In the development 
of the animal body, each vital organ enters upon the 
performance of its function, only after it has finished its 
evolution and acquired its definite texture. There are 
organs even, particularly those which are destined for 
the propagation of the species, which take no part in the 
organic scene until a long time after birth, they then dis- 
appear, to return again to a state of torpor during the 
last period of the life of the individual. The heart, on 
the contrary, manifests its activity from the beginning 
of life, long before it possesses its perfect form and its 
characteristic structure. This fact is not only remarka- 
ble in showing the precocity of the functions of the 
heart, but it is also of a nature to cause the physiolo- 
gist to reflect deeply upon the real connection which 
may exist between anatomical forms, and the vital pro- 
perties of the tissues. 
Nothing is so beautiful as to watch the birth of the 
heart. In the chick, at the twenty-sixth or thirtieth 
hour of incubation, there appears upon the germinal 
plane (or field) a very minute point, the punctum saliens, 
upon which at last may be seen movements, at first 
unfrequent and hardly perceptible. These motions grad- 
ually become more decided, and more frequent; the 
heart is better defined ; arteries and veins pierce it; 
the sanguineous liquid manifests itself more distinctly, ON THE PHYSIOLOGY OF TH,E HEART 
and a provisory vascular system (area vasculosa) is dis- 
played, radiating around the heart, now physiologically 
'constituted the organ of embryonic circulation (Fig. 11). 
Fio. 11.—Area vasculosa, or germinal field, representing the primitive 
circulation of the chick in the egg. 
a. Primitive heart, central apparatus of the circulation. 
At this period, the fundamental lineaments of the body 
of the animal have already appeared: the heart, now in 
full activity, presents an isolated, moving blood point, 
anterior to the organization, and destined to transport 
on the highway of life, the materials necessary for the 
formation of the animal body. 
"While this organ is engaged in the construction and 
development of the whole body, its own volume is in- 
creased and developed. At its beginning, it was a small 
vesicle, obscurely contractile, like the circulatory vesicle A.ND ITS CONNECTIONS WITH THE BRAIN. 
27 
of an infusorial; but this vesicle soon lengthens itself, 
and beats with rapidity; the inferior portion receives 
the blood, and represents an auricle; the superior part 
constitutes a true ventricle, which sends the blood into 
the aortic bulb, dividing into the bronchial arcs—it is 
then the heart of a fish. After a while this heart under- 
goes a motion combined of a twist and see-saw action, 
which brings up the auricular part, and lowers the ven- 
tricular. Before the completion of this see-saw motion, 
the organ presents a heart with three cavities—it is now 
the heart of a reptile—and from the time this movement 
is completed, it possesses the four cavities of the heart 
of a bird or mammal. The various phases in the de- 
velopment of the heart, show us, then, that this organ 
does not reach the most perfect state of organization— 
as in birds, mammals and man—until it has passed 
through the forms which remain definite in the inferior 
classes (Fig. 12). It is the observation of these, and 
many other facts of the same kind, which has given 
birth to the idea, philosophically true, that every animal, 
in its embryonic condition, reflects the organizations 
which are inferior to it.* 
The heart differs, also, from all the muscles of the 
body, in this : that it acts from its first appearance in the 
embryo, and before it is fully developed. Its organiza- 
tion once completed, it still continues to form an excep- 
tion in the muscular system. Indeed, the whole muscu- 
* It is true that the heart of a chicken, during its development, has three 
cavities, and possesses an interventricular septum, ■which does not exist in 
the adult reptile. We must then compare the heart of a chick, during 
development, with the heart of a reptile undergoing development; for it 
may be possible that this interventricular septum existed in the reptile at a 
certain period of development, and that it disappears after a while. 28 
ON THE PHYSIOLOGY OF THE HEART 
lar apparatus presents us with alternations of activity 
and repose ; the heart, on the contrary, is never at rest; 
of all the organs of the body, it acts the longest; it 
Fig. 12.'—Successive periods of the development of the heart of a 
chick. 
A. Primitive heart, formed of but one cavity, v. The arterial and the 
venous heart, not yet being distinct. 
B. Second period of the development of the heart, corresponding to the 
heart of a fish. v. The arterial heart, making tire auricular portion 
placed behind, b. b. The bronchial arteries emanating from the aortic 
bulba. 
C. Same figure as the preceding, seen in profile, v. Arterial heart, o. Ve- 
nous hep,rt. b. Bronchial arcs. 
D. Third period of the development of the heart, corresponding to the heart 
with the three cavities of reptiles, v. v. The two artei’ial hearts, right 
and left, corresponding to the two ventricles, right and left, of the fully 
developed heart, o. o. The two venous hearts, right and left, corres- 
ponding to the two auricles, the right and the left, of the fully developed 
heart, a. Aortic bulb. 
exists before the organism, it survives it, and in the suc- 
cessive and natural death of the organs, it is the last to 
continue to manifest its functions. In a word, to use AND ITS CONNECTIONS WITH THE BKAIN. 
the expression of the great Haller, the heart is the first 
to live (primum vivens) and the last to die (ultimum mo- 
riens). In that extinction of the life of the organism, 
the heart continues to act when the organs are silent 
around it. It is the last awake, as if it awaited the end 
of the struggle between life and death; for so long as it 
beats, life may be re-established ; 'when the heart iias 
ceased to beat, it is irrecoverably lost, and as its first 
pulsation was the certain sign of life, so its last pul- 
sation is the certain sign of death. 
The preceding notions are necessary, as they will 
assist us the better to comprehend the action of the 
nervous system over the heart. We have already per- 
ceived that this muscular organ possesses the property 
of contracting without the intervention of the nervous 
influence. It begins its functions long before the ner- 
vous system has given any sign of life; there is even 
more than this: the nerves may be well developed 
and anatomically constituted, yet without acting on 
any of the muscular organs which are already devel- 
oped. Indeed, I have proved, by direct experiments, 
that the nervous extremities are not physiologically 
fused into the muscular system, except in the last stages 
of embryonic life. After birth, when the nervous sys- 
tem has assumed the control over all of the muscular 
organs of the body; the heart, nevertheless, passes from 
its control, to perform its functions of motor power over 
the central circulation. The muscles of the members of 
the body are paralysed by cutting the nerves which ani- 
mate them : the movements of the heart are never para- 
lysed by dividing the nerves which are spent upon its 
tissue, on .the contrary, its movements become more 
rapid. Those poisons which destroy the properties of 30 
ON THE PHYSIOLOGY OF THE HEART 
the motor nerves, abolish the movements of all of the 
muscular organs of the body, whilst they exert no influ* 
ence over the pulsations of the heart. We have here a 
frog poisoned with curare ; this poison paralyses, par ex- 
cellence, the motor nervous system : you sec that the 
heart continues to beat, and causes the blood to circulate 
through the body of this animal, which is absolutely 
deprived of all motor nervous influence. 
From all of this, shall we conclude that the heart pos- 
sesses no nerves ? This opinion, entertained by the 
older physiologists, is at this day contradicted by anato- 
my. That science shows us that the tissue of the heart 
is abundantly supplied with nerves (Fig. 13). It is not, 
then, to the absence of nerves that we are to attribute 
all of the anomilies that the heart presents ; it depends 
upon a very particular mechanism of the nerves, which 
remains still to be examined. The well known reaction 
of the motor nerves on the muscles in general, resolves 
itself into this fundamental principle: so long as the 
nerve is not excited, the muscle remains in a state of 
relaxation and repose, but when the nerve becomes natu- 
rally or artificially excited, the muscle is thrown into 
action—contraction. The observation of the influence 
of our will over the movements of our limbs, will be 
suflicient to prove what I have advanced, but really 
nothing is more easy of demonstration, by direct experi- 
ments, made on living animals, or on those but recently 
dead (Fig. 13). 
If a frog be prepared by vivisection, so as to insulate a 
nerve which is expended upon the muscles pf a limb, 
we see, that so long as this nerve is not touched, the 
muscles of the limb remain relaxed and in repose, but as 
soon as the nerve is excited by pinching, or better still, 31 
AND ITS CONNECTIONS WITH THE BRAIN. 
by passing a current of electricity through it, the mus- 
cles become energetically and rapidly contracted; here 
is a general fact, which may be experimentally proved 
Fio. 13—The heart, with the nervous branches which it receives from 
the brain. 
C. The heart, a. The carotid artery going to the brain, n. Pneumogaatric 
nerve, the branches of which are distributed to the heart. 
iii man, and all vertebrated animals, either during life 
or immediately after death, so long as the muscular and 
nervous systems preserve their respective vital properties. 32 
ON THE PHYSIOLOGY OF THE IIEAliT 
If now, we act upon the nerves of the heart by analo- 
gous processes, we will see that this paradoxical muscu- 
lar organ presents, in this point of view, an exception ; 
and, to he more explicit, I will even say that it presents 
phenomena absolutely in opposition to those which we 
have observed in the muscles of the extremities. To be 
within the truth, it will suffice to reverse the terms'of 
the proposition, and say, that so long as the nerves of 
the heart arc not excited, it beats and remains in a func- 
tional state ; but if the nerves are excited naturally or 
artificially, it becomes relaxed, and is reduced to a state 
of repose. If a frog, or any other animal, either living 
or recently dead, is prepared, by vivisection, so as to 
observe the heart, and to insulate the pneumogastric 
nerves which are expended in .its tissue, we prove that 
so long as these nerves are not acted upon, the heart 
continues to beat as in ordinary, and as soon as they are 
excited by a powerful electric current, the diastole of the 
heart is arrested, that is to say, relaxation takes place. 
Fig. 14 is a tracing which shows the beginning of re- 
pose of the heart of a frog,* when its pneumogastric 
nerve is excited by electricity. 
Fig. 15 is another tracing showing the entrance to- 
wards the contraction of the muscle on the limb of the 
frog, when the nerve which is expended upon it is ex- 
cited successively and alternately. 
* The paralysing influence of the pneumogastric upon the beatings of the 
heart, is not perfectly expressed in the frog. We here exhibit a tracing ob- 
tained under the same conditions, by Mr. Marey, with the heart of a horse, 
and which very nearly declares an almost absolute arrest of the heart under 
the influence of the irritation of the pneumogastric nerve. But it is under- 
stood, that at the conference in the amphitheatre of the Sorbonue, it was 
impossible to make the experiment upon a horse. AN!) ttS CONNECTIONS \VlTIl THE BRAIN. 
33 
Fig. 14.—Tracing representing the beatings of the heart of a horse, to show the paralysing influ- 
ence of the irritation of the pneumogastric nerve on the contractions of the heart. 
Excitation of the nerve: repose of the heart. 
Fig. 15.—Tracings representing the contractions of the muscles of the foot of a frog, to show that 
the irritation of the nerves provokes these contractions. 
Excitation of tlio nerve: contraction of the mnsolos. 
Repose of the pneumogastric contraction of the heart. 
Repose of the nerve : repose of the muscles 
The result is equally general ; it is produced m all 
vertebrated animals, from the frog to man. It will be 34 
OX THE PHYSIOLOGY OF THE HEART 
necessary, tlien, to have the fact of this singular and 
paradoxical influence of the nerves on the heart always 
before our minds, because it is this result, which will 
serve us as a starting point, in explaining hereafter, how 
the central organ of the circulation can react on our 
perceptions. 
But before considering this point, it is necessary to 
examine more closely the various forms which the stop- 
page of the heart presents under the influence of the gal- 
vanic excitement of the nerves. The excitation of the 
pneumogastric nerves, or the nerves of the heart, by a 
very active electric current, soon arrests the heatings of 
that organ. However, there are always some varieties 
in the phenomena which depend upon the sensitiveness 
of the animal. If very sensitive mammifers be acted 
upon, the heart is instantly' arrested, whilst in cold- 
blooded animals, and especially in the winter, the heart 
does not immediately feel the nervous influence; many 
pulsations may still take place before it is arrested. 
After the cessation of violent galvanic excitation of the 
nerves, the pulsations no longer appear; the arrest of 
the heart is then definite, and death immediately takes 
place. 
Galvanic excitation of the pneumogastric nerves 
arrests the heart so much the more energetically, as the 
application is more sudden, and if it has been seldom 
repeated. When the excitation is repeated many times, 
or when it has been continued for a long time, the sen- 
sibility of the heart and nerves are blunted to such a 
degree that electricity loses its power to arresj; its pulsa- 
tions ; the same takes place when the nerves are gradu- 
ally irritated; very violent currents may thus be succes- 
sively employed without causing arrest of the heart’s AND ITS CONNECTIONS WITH THE BRAIN. 
35 
action. When feeble excitations are applied to the 
nerves of the heart, the results, in the main, are always 
the same; only, the difference of intensity gives them 
another appearance. Indeed, feeble and instantaneous 
galvanic excitation of the pneumogastrics, in a healthy 
and very sensitive animal, produces a sudden arrest of 
the heart; but this arrest is of so short duration, that it 
would often be imperceptible to an unsuspecting ob- 
server. Besides, after these light or moderate actions, 
the cardiac pulsations soon reappear, with more energy 
and rapidity. It is thus seen that the energetic ex- 
citation of the nerves of the heart, brings on a pro- 
longed arrest of that organ, with a return of its beat- 
ings more or less difficult and slow, whilst the mode- 
rate actions only provoke a very fleeting arrest of the 
heart’s action, immediately followed by an acceleration 
in the pulsations, with an increase of the energy of the 
ventricular contractions. 
All of the results which we have mentioned, whether 
relating to the excitation of the nerves which are dis- 
tributed to the muscles of the limbs, or to the excitation 
of the nerves of the heart, have been furnished by ex- 
periments of vivisection, in which the excitant was 
applied to the motor nerves themselves. But in the 
natural state, things do not go on in this way; there are 
physiological excitants which irritate the motor nerves 
so as to determine their reaction on the muscles. These 
physiological excitants are two in number, the will and 
sensation, or sensibility. The will cannot exercise its 
influence on all of the motor nerves of the body; the 
nerves of the heart, for example, are beyond its influ- 
ence. Sensation, on the contrary, exercises an influence 
which is general; and all of the motor nerves, be they ON THE PHYSIOLOGY OK THE HEART 
voluntary or involuntary, submit to its reflex action. 
All sensitive actions, which react on the motor nerves, 
and give rise to involuntary movements, are called reflex; 
because it is supposed that the sensitive impression, 
coming from the periphery, is reflected at the nervous 
center upon the motor nerve. 
It will be useless to extend our remarks any farther’ 
on the mechanism of reflex nervous actions, which, at 
this day, forms one of the most important liases of the 
physiology of the nervous system. It will sufflee us to 
know, that all involuntary movements are the result of 
the simple action of sensation, or of the sensitive nerve 
upon the motor nerve, which then reacts on the muscle. 
All of the involuntary movements of tho heart that we 
shall have to observe, have no other origin than the re- 
action of sensation on the motor pneumogastric nerves 
of that organ ; and when we say, for example, that a 
painful impression arrests the movements of the heart, 
we simply signify that a sensitive nerve, primitively 
excited, has transmitted its impressions to the heart 
by exciting the pneumogastric, which, in its turn, has 
caused its motor influence to be felt by tho heart, ab- 
solutely, as when wo act in our experiments with the 
galvanic current. When the physiologist provokes a 
motor nerve to react on the muscles by means of a gal- 
vanic current, or by pinching, he substitutes an artificial 
for a natural excitant, which is the will, or the sensi- 
bility; but the results of the nervous motor action are 
always the same. It will soon be seen, that all of the 
forms of arrest of the heart’s action which we have 
observed, by acting directly with the galvanic agent 
on the pneumogastric, reproduce themselves, in conse- 
quence of various sensitive influences. As we now AND ITS CONNECTIONS WITH THE BRAIN. 
know that sensitive influences can act on the heart, by 
exciting its motor nerves, we can then understand that 
intermedium of language, and when we say: that the 
sensibility, or the sentiments, react on the heart, you 
will know what that signifies, physiologically. 
Our direct experiments on the excitation of the pneu- 
raogastric nerves, have shown us, that the more sensi- 
tive the animal is, so much the more prompt is the heart 
in receiving nervous impressions, and to be arrested in 
its actions ; it is the same for the reactions of the 
sensitive nerves on the heart. In the frog the heart is 
not arrested by pinching the skin; more energetic means 
are necessary to produce this effect; hut in animals 
higher in the scale—in certain races of dogs, for exam- 
ple—the slightest excitations of the sensitive nerves 
show their effect upon the heart. If a hoemamometer be 
placed on the artery of one of these animals, so as to 
have the expression of the pulsations under our eyes, 
by the oscillation of the mercurial column, we will ob- 
serve, at the moment when a sensitive nerve is rapidly 
excited, that there is a stoppage in the diastole of the 
heart; this brings about a suspension of the oscillation, 
with a slight lowering of the mercurial column. Soon 
afterwards, the pulsations reappear, considerably accele- 
rated, and more energetic; for the mercury is raised, 
sometimes many centimetres, to return to its primitive 
point; when the heart becomes calm, and resumes its 
natural rythm. The heart is sometimes so sensitive in 
certain animals, that very slight excitations of the sensi- 
tive nerves may bring on reactions, even when the animal 
manifests no sign of pain. These are some of the ex- 
periments performed by my piaster, Magendie, and my-, 38 
ON THE PHYSIOLOGY OF THE HEART 
self, many years ago, and which have been often repeated 
and verified by various processes. 
In proportion as the animal is elevated in the scale of 
organization, the heart becomes a more and more deli- 
cate reagent, to convey the sensitive impressions which 
take place in the body ; and it is natural to think that 
man, in this connection, should hold the first rank. In 
him the heart is not only the central organ of the cir- 
culation of the blood, but it becomes also a center where 
all of the sensitive nervous actions expend themselves. 
The nervous influences which react on the heart, come 
either from the periphery by the cerebro-spinal system, 
or from the internal organs by the great sympathetic, or 
from the cerebral center itself; for in a physiological 
point of view, the brain should be considered as the 
most delicate of all the neivous surfaces: whence it 
results, that the sensitive actions which are derived from 
this source, are those which exercise the most energetic 
influence over the heart. 
How is it possible to conceive of the physiological 
mechanism, by the aid of which, the heart is connected 
with the manifestation of our sentiments? AVe know 
that this organ can receive the contre coup of all the sen- 
sitive vibrations which take place in us ; and that some- 
times, if the impression has been very strong, there results 
from it a violent arrest, with momentary suspension and 
feebleness of the circulation: if the impression has been 
slight or moderate, a slight arrest, with reaction and 
increase in the number and the energy of the cardiac 
pulsations. But how, then, can this state translate our 
sentiments ? This is the question which needs an ex- 
planation. 
Let us remember that the heart never ceases to be a AND ITS CONNECTIONS WITH THE BfcAIN. 
forcing pump; that is to say, a motive power, which 
distributes the blood to all of the organs of the body. 
If it stops, there is necessarily a suspension or diminu- 
tion in the supply of the vital liquid to the organs, and 
as a consequence, suspension or decrease in their func- 
tions. If, on the other hand, the slight arrest of the 
heart’s action is followed by an increased intensity in its 
action, a large quantity of blood is distributed to the 
organs, and as a consequence, there is an exaggeration 
of their functions. However, all of the organs of the 
body, and all of the organic tissues, are not equally sen- 
sitive to these variations of the arterial circulation, 
which may quickly diminish or increase the quantity of 
the nutritious liquid which they receive. The nervous 
organs, and above all, the brain, which constitutes the 
apparatus whose texture is the most delicate, and the 
superior of all in the physiological order, receives the 
first contre coup of these circulatory disturbances. It is 
a general law for all animals, from the frog to man; that 
suspension of the circulation of the blood, in the first 
place, brings about loss of the cerebral and nervous func- 
tions, in the same way, as an exaggeration of the circu- 
lation exalts the central and nervous manifestations. 
Nevertheless, these reactions of a modified circulation 
on the nervous organs demand very different periocfi, 
according to the species; the time it takes to affect cold- 
blooded animals, is very long, especially in the winter; 
a frog remains several hours before he experiences the 
consequences of the arrest of the circulation ; the heart 
may be taken from it, and for four or five hours after, 
it continues to jump and swim, without appearing to 
have had either its will or its movements disturbed in 
the slightest degree. In warm-blooded animals it is alto- 40 
on The physiology of the Heart 
getlier different; cessation of the heart’s action causes 
the cerebral phenomena to disappear very rapidly, and 
this takes place much more easily, as the animal is high 
in the scale of organization ; that is to say, as it pos- 
sesses a more delicate nervous organization. Reason and 
experiment show us that in this respect man ought to hold 
the first rank; his brain is so delicate that he will expe- 
rience, in a few seconds, almost instantaneously, the 
reverberation of the nervous influences exercised on the 
central organ of the circulation; influences which, you 
will soon see, translate themselves sometimes by an 
emotion, and sometimes by syncope. Physiological 
phenomena everywhere pursue one identical law in all 
animals; but the more or less delicate nature of the 
living organism gives them an entirely different expres- 
sion ; thus the law of the reaction of the heart on the 
brain, is the same in the frog and in the man ; the frog, 
however, can never experience an emotion or a syncope, 
because the time necessary for its heart to feel the ner- 
vous influence, and its brain to experience the circula- 
tory impulse, is so long, that the physiological relation 
between the two disappear. In man, the influence of 
the heart on the brain is translated by two principal con- 
ditions, between which many intermediate ones may be 
Apposed: these are syncope and emotion. 
Syncope is due to a momentary cessation of the cere- 
bral functions, in consequence of an interruption in the 
supply of arterial blood to the brain. Syncope may be 
produced by tying, or directly compressing all of the 
arteries which go to the brain; but we will occupy our- 
selves at this time only with syncope which occurs in 
consequence of a sensitive influence carried to the heart, 
and energetic enough to arrest its beatings. The arrest AND ITS CONNECTIONS WITH THE TRAIN. 
of the heart’s action which produces loss of conscious- 
ness, by depriving the brain of blood, also brings about 
pallor of the countenance, and a crowd of other acces- 
sory effects, which have nothing to do with the question 
now under consideration. All energetic and sudden 
sensitive impressions, whatever else may be their na- 
ture, may bring on syncope. Physical impressions on 
the sensitive nerves, moral impressions, or painful and 
voluptuous sensations, conduce to the same result, and 
bring on the arrest of the heart’s action. The duration 
of syncope is naturally connected with the duration of 
the stoppage of the heart. The more intense the arrest 
has been, the longer, in general, will the syncope last; 
and the more difficult will it be to re-establish the car- 
diac pulsations, which at first, return irregularly, and 
but slowly resume their normal rythm. Sometimes the 
arrest of the heart is final, and the syncope is mor- 
tal—this may take place in very feeble, and at the same 
time very sensitive, individuals. It has been proved, 
experimentally, that at times, it is only necessary to pro- 
duce an acute pain, by pinching a sensitive nerve, to 
bring about a definite arrest of the heart, and mortal syn- 
cope in doves, wasted by starvation. 
Emotion arises from the same physiological mech- 
anism as syncope, but it has an entirely different 
manifestation. Syncope, which takes the blood from 
the brain, gives a negative expression, proving that 
a violent nervous impression has gone to reflect itself 
on the heart, to rebound on the brain. Emotion, 
on the contrary, sends to the brain a more active 
circulation, and gives a positive expression; in this 
sense the cerebral organ receives a functional super- 
excitement, in harmony with the nature of the nervous ON THE PHYSIOLOGY OF THE HEART 
influence which has brought it on. In emotion, there is 
always an initial impression, which in some way sur- 
prises, and very slightly arrests, the heart’s action, and 
consequently excites a feeble cerebral shock, producing 
a fleeting pallor of the countenance ; the heart, like an 
animal pricked by a spur, soon reacts, quickens its pace, 
and sends the blood in full tide through the aorta, and all 
the other arteries. The brain, the most sensitive of all 
of the organs, immediately, and before all of the others, 
feels the effect of this modification of the circulation. 
The brain is doubtless the starting point of the nervous 
sensitive impression; but b} the reflex action on the 
motor nerves of the heart, the sensitive influence has 
provoked the conditions in the brain which are con- 
nected to the manifestation of sentiment. The heart is 
no more the seat of our sentiments than the hand is the 
seat of our will; but the heart is an instrument which 
concurs in the expression of our sentiments, as the hand 
concurs in the dictate of the will. 
In fine, the heart of man is the most sensitive of all 
the organs of vegetative life; it is the first to re- 
ceive the cerebral nervous influence. The brain is the 
most sensitive of the organs of animal life: it receives 
the first fruits of the circulation of the blood. The 
result is, that these two culminating organs of the living 
machine are connected in ceaseless action and reaction. 
The heart and brain are, then, in solidarity of reciprocal 
actions of the most intimate character; actions which 
increase and decrease in proportion as the organism be- 
comes more delicate and more developed. These con- 
nections may be constant or fleeting, varying with the 
sex and age of the animal. It is thus, that at the period 
of puberty, when the organs, until then imperfect and AND ITS CONNECTIONS WITH THE BRAIN. 
inert, are awakened and developed, giving birth to sen- 
timents in the brain, until now unknown, and bearing to 
the heart new impressions. The Sentiments we expe- 
rience are always accompanied by reflex actions of the 
heart; it is from this organ that the condition necessary 
for the manifestation of sentiments proceeds, although 
the brain may be their exclusive seat. In the more 
elevated organisms, life is but a continual exchange 
between the sanguineous and nervous systems. The 
expression of our sentiments is made by an exchange 
between the heart and the brain, the two most perfect 
wheels of the living machine. This exchange is carried 
on by well known anatomical mechanism; by the 
pneumogastric nerves, which transmit the nervous influ- 
ence to the heart; and by the carotid and vertebral 
arteries, which convey the blood to the brain (Fig. 16). 
The whole of this wonderful mechanism depends, then, 
upon a thread, and if the nerves which unite the heart 
to the brain should be destroyed, this reciprocity of 
action would be interrupted, and the manifestation of 
our sentiments very seriously disturbed. 
All of these explanations, I may be told, bear the 
impress of materialism. To that I will reply, that it is not 
the question under consideration. If it did not take pae 
too far from our inquiries, I could easily show you, that 
in physiology, materialism leads to nothing, and proves 
nothing; but I will ask ; is a concert of musical instru- 
ments less ravishing, because the philosopher calculates 
mathematically all of its vibrations ? Is a physiological 
phenomenon less wonderful because the physiologist has 
analysed all of its material conditions ? It is very ne- 
cessary, then, that these analyses should be made, that 
these calculations should be pursued, for without them ON THE PHYSIOLOGY OF THE HEART 
there would be no science. Then physiological science 
teaches us that outlie one side, the brain really recci ves 
tlie impression of all of our sentiments, and on the 
Fig. lti.—The anatomical connections of the heart with the brain, 
by the carotid arteries and the pneumogastric nerves, to explain 
the reactions of these two organs upon each other. 
C. The heart, a. 1 he carotid artery going to the brain, n. Pneun 
nerve, th e branches of which arc distributed to the heart. 
other side, that the heart reacts by sending to the brain 
the necessary conditions for the manifestation of these AND ITS CONNECTIONS WITH THE DRAIN. 
45 
sentiments, lienee it results that the poet, and the man 
of romance, appeal to our hearts to affect us, that the 
man of the world, expressing his sentiments at the same 
time by calling- upon his heart, uses metaphors which 
correspond to physiological realities. Sometimes a 
word, a souvenir the sight of a passing occurrence, 
awaken in us a deep and intense suffering; this word, 
this memory, may not be painful in themselves, but are 
so onty in the phenomenon they excite. When any one 
says that his heart is broken with grief, real phenomena 
are produced in the heart—its action has been arrested— 
if the painful impression has been too sudden, the blood 
does not reach the brain—syncope and nervous crises 
are the consequence. There is, then, good reason, when 
any one has terrible news to impart, which could cause 
great mental distress, why it should be conveyed with 
the utmost caution. 
By our experiments on the nerves of the heart, we 
know that excitants gradually applied to the heart, blunt 
or decrease the sensibility of that organ, without pro- 
ducing arrest of its pulsations. 
When any one says that he has a full heart, after 
having suffered agony for a long time, or having expe- 
rienced painful emotions, this also responds to particular 
physiological conditions of that organ ; prolonged pain- 
ful impressions, become incapable of arresting the 
heart’s action ; they fatigue and wear it out, retarding 
its pulsations, prolonging its diastole, and producing in 
the precordial region a sense of fulness or contraction. 
Agreeable impressions also correspond to particular 
states of the heart. When a female is surprised by a 
pleasant emotion, the words which have given it birth 
have flashed through the mind like lightning, without ON THE PHYSIOLOGY OF THE HEART 
stopping there ; the heart has been momentarily attacked 
in advance of all reasoning or reflection. Sentiment 
begins to manifest itself after a slight arrest of the 
heart, which may be imperceptible to all save the physi- 
ologist; the heart, pierced by a nervous impression, 
reacts in palpitations, which cause it to bound and 
beat more violently against the breast, at the same time 
that it sends the blood to the brain, whence results the 
blush of the face, and the peculiar expression of the 
features, expressive of pleasure. To say that love causes 
the heart to palpitate, is not only a poetic form of speech, 
it is also a physiological reality. When any one says 
that lie loves with all of his heart, this physiologically 
signifies that somebody’s presence, or his memory, 
awakens a nervous impression, which, transmitted to 
the heart by the pneumogastric nerves, causes that organ 
to react in a way most conduciye to arouse in the brain 
a sentiment or emotion of affection. I suppose, be it 
well understood, that the avowal is sincere ; without 
this, the heart will not be affected, and the sentiment 
would only be lip-service. 
When it is said that great thoughts spring from the 
heart, it is equivalent to saying that great thoughts come 
from sentiment, for our sentiments, which have their 
physiological starting point in the nervous centers, act 
on the heart as peripheric sensations. The brain of man 
should have the heart at its service to express its senti- 
ments, Two hearts united, are hearts which beat in 
unison under the influence of the same nervous impres- 
sions; hence result the harmonic expression of similar 
sentiments. 
Philosophers say that one can rnaster his heart and 
silence his passions. These are expressions which physi- AND ITS CONNECTIONS WITH THE BRAIN. 
47 
ology can interpret: It is known that, by the power of 
will, man may control many of the reflex actions due to 
sensations produced by physical causes. Reason, with- 
out doubt, exercises the same empire over the moral 
sentiments. Man may, then, become able, through the 
power of reason#to prevent certain reflex actions from 
being effected upon the heart; but the greater the tri- 
umph of pure reason, the weaker will sentiment become. 
The nervous power capable of arresting reflex ac- 
tions in general, is less in woman than it is in man: 
it is this which has given her the supremacy* in the do- 
main of physical and moral sensibility ; it is this which 
lias celebrated her as having a heart more tender than 
that of man. 
But I must bring these considerations, which would 
involve too much time, to a close, by a general con- 
clusion. 
Science does not contradict the observations and data 
of art, and I cannot subscribe to the opinion of those 
who believe that the positive character of science must 
prove fatal to inspiration. According to my views, I am 
obliged to come to another and contrtiry conclusion. 
The artist may find in science the most solid founda- 
tions, and the savant may draw from art the most 
assured intuition. Science, although advanced, is still 
very imperfect, and critical periods may arise, which 
harrass and disturb, rather than aid the artist. This 
may be the case with physiology, at the present time, 
as respects the poet and the philosopher. This is but 
a transitory state, and I am convinced, that when 
physiology shall be sufficiently advanced, the poet, the 
philosopher and the physiologist will understand each 
other.