AN 
EXPERIMENTAL AND ANALYTICAL 
ESSAY, 
ON 
THE POWERS 
BY WHICH 
THE BLOOD IS CIRCULATED 
IN 
THE VEINS. 
MAURICE FITZ GIBBON, M. D. 
PHILADELPHIA: 
PRINTED BY J. R. A. SKERRETT. 
1833. TO 
SAMUEL. JACKSON, M. D. 
PROFESSOR OF THE INSTITUTES OF MEDICINE AND CLINICAL MEDICINE IN THE 
UNIVERSITY OF PENNSYLVANIA; LECTURER ON THERAPEUTICS AND 
MATERIA MEDICA IN THE PHILADELPHIA MEDICAL INSTITUTE: 
VICE PRESIDENT OF THE PHILADELPHIA MEDICAL 
SOCIETY; VICE PRESIDENT OF THE 
COLLEGE OF PHARMACY, &C. 
THIS ESSAY, 
THE FRUITS OF PHYSIOLOGICAL INVESTIGATIONS, COMMENCED 
BY HIS ADVICE, AND PURSUED IN A SPIRIT, TEMPERED, 
GUIDED, AND CHERISHED BY HIMSELF, 
IS, 
WITH THE SENTIMENTS OF THE HIGHEST REGARD FOR HIS EMINENT 
TALENTS AND PROFESSIONAL ZEAL, AND OF UNFEIGNED 
ADMIRATION FOR HIS MANY PRIVATE VIRTUES, 
MOST RESPECTFULLY DEDICATED. 
BY 
HIS EVER GRATEFUL FRIEND AND PUPIL, 
MAURICE FITZ GIBBON. ESSAY, &c. 
The powers which circulate the blood, have been subjects of in- 
quiry ever since the great discovery of the circulation, and numerous 
are the opinions that have been offered to account for the motion of 
this fluid; and yet it may be fairly asked, what do we really know, 
on which there rests no doubt in addition to these facts, that the 
blood is circulated, and that it acquires motion by the contraction of 
the heart. It is true we do know a little more, but this little has 
been, I think, greatly overrated, both in respect to its importance, 
and the degree of certainty which is attached to it. 
Notwithstanding all that has been said on the subject of the dias- 
tole of the cavities of the heart, it is not yet generally understood, 
whether the fibres of the heart are active or passive while the diastole 
is being effected,-i. e. whether the fibres constituting the muscular 
parietes of the auricles and ventricles of the heart, are relaxed in 
each cavity during the time in which they receive blood, or whether 
they are actively concerned in dilating the cavity into which the 
blood enters. The opinion of Harvey is that which almost generally 
prevails in the schools. He contended that a state of inertia or re- 
laxation succeeded to the systole of the heart, and that the heart 
itself is the sole mover of the blood. Thus supposing the auricles 
to be full of blood, and the ventricles empty; the former, according 
to his view, contract, force the blood into the latter cavities, separate 
their relaxed walls from each other, and distend them. The ventri- 
cles now filled with blood, contract; the tricuspid and mitral valves 
are closed by the pressure made on the blood; the semilunar valves 
are opened by the same cause; the blood is forced into the arteries of 
the greater and lesser circulation, it moves onwards through the arte- 
ries into the veins, back again through the latter vessels to the auri- 
cles of the heart with undiminished velocity, and these cavities it 
enters, dilates, &c. The blood from the right ventricle goes through 
the arteries of the lungs, and from these into the pulmonary veins, 
thence into the left auricle. The left auricle forces it into the left 
ventricle, which contracts, forces it into the aorta, thence into all 
parts of the system, from which it is continued in motion by the force 
impressed upon it, into the veins, and by these to the right side of 
the heart. 
Of all the modern writers who adopt the above opinion, there is no 
one who is less equivocal in his belief of it than Dr. Barry. “ The 6 
supposition,” he says, “that the cavities of the heart possess the 
power of dilating themselves, and therefore of acting alternately as 
suction and forcing pumps, although adopted by some physiologists, 
has hitherto derived but little support either from anatomy or expe- 
riment. This opinion was too trite, even in the days of Harvey, to 
merit serious refutation. Neither the auricle nor the ventricle ap- 
pears to be furnished with any intelligible muscular apparatus, by 
which either can accomplish its own dilatation.” 
Although the opinion of those who contend for the active diastole 
of the heart is not incompatible with the peculiar doctrine of Dr. 
Barry on the “ influence of atmospheric pressure upon the progression 
of the blood in the veins,” still it seems to be any thing but pleasing 
in his sight, and creditable in his estimation. Were Dr. Barry to 
view the influence of the active diastole in the light I do, he might 
acknowledge that it is real, and yet not fear for the credit of his own 
views. But Dr. Barry, in denying the diastole to be active, denies, 
in fact, what he appears to aim at, that is, the suction power of the 
heart. It would appear, if we may be permitted for a moment to 
look into Dr. Barry’s sentiments respecting his discovery, that he 
strongly apprehended a rival pump in the diastole of the heart, even 
though he assures us, “ the supposition that the cavities of the heart 
possess the power of dilating was too trite even in the days of Harvey, 
to merit serious refutation.” Now I admit that Dr. Barry’s views 
on the influence of respiration are not without proper foundation, but 
in my opinion he has greatly overrated the influence actually exerted 
by that power. Those also who have contended that the heart acts 
as a powerful sucking pump, have also, in my opinion, been equally 
in error with Dr. Barry; while the views of Harvey, though forcibly 
objected to by all who contend for the powerful influence of suction in 
one or the other way, appear liable but to a few objections. An in- 
quiry into the influence of the agents to which I have now alluded, 
will constitute the principal subject of this paper. 
Active diastole of the heart.'—Experiment has proved in the hands 
of many, who have carefully investigated the subject, the active dias- 
tole of both the auricles and ventricles to be real, contrary to what 
Dr. Barry asserts; and we can oppose to his opinion on the subject, 
that of Bichat, Magendie, Richerand, Languish, Hamberger, 
and several other eminent physiologists. Still more recently we have 
the authority of Dr. Thomas Robinson, of Virginia, a highly talented 
physiologist, who published his remarks on the circulation of the 
blood in the 22d No. of this Journal. 
Richerand, it must not be concealed, has used the following lan- 
guage:—“ The cavities of the heart, however, are not entirely pas- 7 
sive during dilatation;” and this leaves me somewhat at a loss how 
to consider his opinion on this subject, for I do not believe simply in 
a diastole, in the least extent passive, but fully and completely active 
However, he either believed in the active diastole of the heart, or 
was most inconsistent with the results of his own observations, for 
he also says, “ if you attempt to check the diastole of the heart, this 
organ resists the hand which compresses it, and its cavities appear 
endowed with a power which Galen termed pulsive; in virtue of 
which, they dilate to receive the blood, and not became they receive it.” 
Magendie also observes—“ all that has been said of the force of 
the heart, relates only to its contraction, its dilatation having been 
considered as a passive state, a sort of repose of the fibres; however, 
when the ventricles dilate, it is with a very great force, for example, 
capable of raising a weight of twenty pounds, as I have many times 
observed in animals recently dead. "When the heart of a living ani- 
mal is taken hold of by the hand, however small it may be, it is im- 
possible by any effort to prevent the dilatation of the ventricles. The 
dilatation of the heart then cannot be considered as a state of inaction 
or repose. 
Even Bichat, who lays a lower estimate on the influence of the 
heart in circulating the blood, than any other physiologist, says, 
“we shall see that this kind of motion is real to a certain extent, 
both in the heart and the organic vessels. But here it is wholly dif- 
ferent; the heart dilates of itself when it is empty, as we see by draw- 
ing it out of a living animal, and by emptying it afterwards of the 
fluid it contains, because it has in itself the cause of dilatation.” 
We do not find in the works of the older physiologists, opinions 
similar to those I have now given, for reasons I shall hereafter notice; 
but that Harvey, Haller, and others felt the heart dilate as forcibly as 
Bichat, Magendie, and Richerand, cannot be doubted; they however 
did not understand it alike with those who have entertained the op- 
posite opinion. 
I might go on to show, that the diastole is active, by many other 
authorities who have observed and described the action of the heart, 
were it really necessary. But I cannot omit referring to the case of 
Dr. Robinson, in a previous No. of this Journal, in which the 
active diastole is so fairly and satisfactorily observed, as to remove 
whatever doubt may still exist on the subject. 
I should be guilty of an unpardonable omission were I at this time 
to leave unnoticed the view of Dr. Hope, of London, “ of the phy- 
siology of the heart’s action,” which he terms new in the very title 
page of his “ Treatise on the Diseases of the Heart and Great Ves- 
sels,” published in 1832. This view, notwithstanding the great pre- 8 
caution which the author used to obtain correct results in his expe- 
riments, appears to us to be extremely erroneous, and calculated to 
misguide every person who may confide in the principles which he has 
laid down. While I thus openly express my sentiments as to the 
character of the work of Dr. Hope, I can with pleasure say, that 1 
have no where met the action of the heart so faithfully, fully, and, in 
my opinion, correctly described. His experiments are minutely de- 
tailed, and I am satisfied every particular as it appeared is correctly 
recorded; but he did not permit his views to be governed by his ex- 
periments, and the exact observations which he took the trouble to 
make. 
It is scarcely necessary to remark that the rythm, or order of suc- 
cession in the action of the heart, is a matter of the highest import- 
ance to be understood, and this of course can only be the case when 
the action of the heart itself is distinctly known. According to the 
observations of Dr. Robinson, the following is the order of succes- 
sion—diastole, systole, repose, and, as he observes, “Bichat’s ex- 
periments led him to the same conclusion,” and presently I shall 
show, from Dr. Hope’s account of his own experiments, that he has 
seen exactly the same thing with Dr. Robinson. The rythm, accord- 
ing to Dr. Hope, is systole, diastole, repose. I conceive the entire 
error of Dr. Hope to arise from the following opinion, with which he 
almost commences his book. Speaking of the diastole of the heart, 
he remarks, “ it is perhaps safer for the present to attribute the dias- 
tole to that power by which a muscle reverts from the state of con- 
traction to that of relaxation, and which I shall, for the sake of avoid- 
ing circumlocution, designate by the term elasticity.” Now, this 
diastole Dr. Hope terras active, but let it not by any means be un- 
derstood that this diastole is the same as that which I contend for. 
Again, Dr. Hope says, “the systole is followed by a diastole, which 
is an instantaneous motion, accompanied with an influx of blood from 
the auricles.” I have now only given what we may consider as mere 
opinions of Dr. H. but in the following we have in his own words 
also an account of an experiment. “I found the auricle to contract 
first, not slowly, but with a motion so rapid as to be almost instanta- 
neous; the moment the fluid reached the ventricle the latter was seen 
to start up evidently by the contraction of its fibres on the fluid which 
it contained, and not by passive dilatation. This more fully proved 
at a later period of the experiment, when the action of the heart was 
from time to time suspended, and the ventricle lay quiescent, though 
partially distended with blood, for then the auricle often made two or 
three contractions which had no stimulant effect on the ventricle, 
while a fourth, not more violent than the preceding, and therefore 9 
not injecting more blood, caused it to spring up in the manner al- 
ready described.” Dr. Hope then unquestionably saw and remarked 
what I consider to be the active diastole. This very “ starting up” 
of which he speaks, I regard as an active diastole, and such it must 
be regarded, unless we grossly misinterpret its character; his own 
words, in fact, are so plain on this subject, that they need no com- 
ment to show that he most assuredly saw the heart dilate, but as this 
probably did not agree with his preconceived notions, he did not see 
it to advantage. 
Dr. Hope has seen the ventricle start up by the contraction 
of its fibres, “ and not by passive dilatation.” Dr. Robinson felt the 
ventricles suddenly spring dilated with surprising force;” have these 
gentlemen, then, not seen and felt exactly the same thing? i. e. have 
they not observed an active diastole of the heart? Certainly they have. 
Dr. Hope has also afforded us another evidence in favour of the 
active diastole of the heart; he says, “ the ventricle lay quiescent 
though partially distended with blood, for then the auricle often made 
two or three contractions which had no stimulant effect on the ven- 
tricle; while a fourth, not more violent than the preceding, and there- 
fore not injecting more fluid, caused it to spring up in the manner 
already described.” Here, then, we perceive that without the power 
to dilate actively, the auricles could not distend or fully expand the 
ventricle. Mr. Brodie, and many other physiologists have witnessed 
the same want of power in the auricles; but they did not recognise 
that a diastole and not a systole followed the contraction of the auri- 
cles. I have seen the auricles contract and dilate in animals as many 
as seven times for one of the ventricles when the lungs were col- 
lapsed, but when respiration was maintained by artificial means the 
ventricles recovered to a considerable extent their power of acting. 
“ The fourth contraction,” says Dr. H. “ caused the ventricles to 
spring up.” What an illogical conclusion is this! how easily refuted! 
as if, indeed, the power of the auricles were the cause of the dilata- 
tion of the ventricles. 
Dr. Hope supposing that the diastole follows the systole, speaks of 
blood entering the ventricles:—“ The systole is followed by a dias- 
tole, which is an instantaneous motion, accompanied with an influx 
of blood from the auricles by which the ventricles reexpand.” This 
I know to be incorrect as a general rule; in some animals I have no 
doubt blood may enter the ventricles at the commencement of the 
repose from the auricles, but in my own experiments I have seen the 
ventricle of the frog’s heart after contraction, small, pale, and void 
of blood, and suddenly it would “start up” and instantly receive 
blood and expel it again, and suddenly return to the state of repose In contracting, the heart is thrown into a state from which it re- 
bounds, or falls back again, as Dr. Robinson described it, to the 
“ stillness of death,” and although in the regular or natural fi’equency 
of action this is but a moment of repose, yet so perfectly at rest are 
the ventricles, that this time of repose, even though it be but for the 
third of a second, is so well marked and evident, that we are always 
struck with it in observing the action of the heart. What is meant 
by the “ stillness of death” will be understood when the heart is ob- 
served just when it is removed from an animal after its life has dis- 
appeared, or in observing a heart in action, it will be perceived that 
the time of repose becomes longer as life declines. When an animal 
is struck on the head, and in this way made insensible, on opening 
its thorax and pericardium we find the heart in a state of rapid and 
violent action ; in a short time it becomes slower and more regular in 
its movements, the times of repose become gradually longer, until 
finally the scene closes and all is at rest. The heart however under- 
goes no sudden change in its appearance. The repose in death re- 
sembles the last repose in life, except in its duration. On cutting 
through the ventricles of the heart soon after they have died, we find 
in some cavities of considerable size, in others the walls closely ap- 
proximated. In the latter state I have found the hearts of birds, frogs, 
and some other animals; while in others again, the cavities were 
much larger, but capable of becoming much more capacious. 
As the heart then, in many cases, presents the ventricles by no 
means dilated in the state of repose, and consequently containing 
but little or no blood in that state, it is evident, I think, that all who 
have described the diastole of the ventricles as preceding the state of 
repose, and succeeding the systole, have greatly erred. The ventri- 
cles unquestionably return to the state of repose with some force, and 
all the appearance of being contracted in that state is absent; the 
ventricles really appear at rest, and the form which they have then 
is not different from what they present soon after death: this is in 
my opinion a state of relaxation as complete as that which any other 
muscle of the body enjoys, but the appearance here is somewhat dif- 
ferent, for the ventricles feel firm and rather unyielding. The ven- 
tricles then, in the state of repose, I do not believe to be under the 
influence of any power tending to dilate or contract them, and here 
I must differ from Dr. Robinson, who says “ the antagonizing powers 
were merely in equilibrio,” or that “ probably the contracting power 
predominated.” This opinion, it will be seen, quadrates perfectly 
and without any forced effort, with the result of my experiments on 
the structure of the heart. 
The active diastole of the auricles, though less striking than the 11 
diastole of the ventricles, is notwithstanding not less real. It is how- 
ever not powerful like that of the ventricles, but it happens equally 
quick with it. The active diastole of the auricles did not escape the 
notice of Magendie, who remarks, “ I have said that the blood of the 
three veins that are in the right auricle makes a considerable effort 
to penetrate into it. If it is contracted this effort has no effect, but as 
soon as it dilates the blood enters its cavity, fills it completely, and 
even distends the sides a little; it would immediately enter the ven- 
tricle if it did not contract itself at this instant. The blood, then, 
confines itself to filling up exactly the cavity of the auricle; but this 
very soon contracts, compresses the blood, which escapes into the 
place where there is least compression; now, it has only two issues- 
Ist, by the vena cava; 2d, by the opening which conducts into the 
ventricle. The columns of blood which are coming to the auricle 
present a certain resistance to its passage into the cavse or coro- 
nary veins. On the contrary, it finds every facility to enter the ven- 
tricle, since the latter dilates itself with force, tends to produce a 
vacuum, and consequently draws on the blood instead of repulsing 
it.” The same is true for the opposite side of the heart. I have here 
quoted at length the opinion of Magendie, not only in relation to the 
diastole of the auricles, but on other points of much importance, be- 
cause I am convinced, by repeated observations on the action of the 
heart, of their correctness. 
In the 12th Yol. of the Philadelphia Journal of the Medical and 
Physical Sciences, (for 1826,) Dr. Hays published his views on the 
forces by which the blood is circulated. On this subject he observes, 
that “ in vain some physiologists have contended that the heart is di- 
lated, and does not dilate itself, and that this dilatation is absolutely 
passive; the dilatation of the heart is a true effort, an active move- 
ment,” &c. 
Dr. Robinson says, “ the diastole appeared to commence in the 
venous sinus, and pass without interruption and with immense velo- 
city to the apex; the systole pursued the same course with equal ve- 
locity.” There is then no alternation according to this gentleman in 
the action of the auricles and ventricles; they are in a state of repose 
at the same time, they dilate at the same time, they contract at the 
same time only with this difference, that action always commences in 
the auricles and extends into the ventricles without interruption.” 
The description of the action of the heart given by Magendie ap- 
pears to me to be more in accordance with facts than that of Dr. Ro- 
binson. Dr. Hope’s opinion on this subject is less exceptionable than 
Dr. R.’s. He has not represented phenomena as they appeared to 
him, out of their natural order, but he failed exceedingly, as I think 12 
I have already shown, in not recognising them in their true charac- 
ter: he admits that the systole of the auricle is followed by the dila- 
tation of the ventricle; but he erroneously considered the diastole 
thus produced as the consequence of the preceding auricular systole, 
and not what resulted from the “true effort,” “the active move- 
ment” of the ventricle itself. He also mistook the repose of the ven- 
tricles for a state of distention; which indeed could not be called with 
propriety a state of repose; and the collapse of the heart after the sys- 
tole, he mistook for an active diastole, and by this last error he was 
led into false principles. Dr. R. however, has not expressed his opi- 
nions without doubt, and if there be any room to object to his having 
ventured to institute principles, I think it must be, that he never ex- 
tended his observations beyond the case which he has published. Leav- 
ing the views then of these gentlemen for the further examination of 
those who may be particularly interested in the improvement of aus- 
cultation, I now return to the subject with which I am at present 
more particularly but here again I find myself opposed to 
the opinions of Dr. R. in a new point of view. 
“ While Bichat,” says Dr. Robinson, “ affirms that the heart di- 
lates with a force which no effort of the hand could prevent, is it not 
surprising that he has neglected to supply a power so great and so 
obvious to the elucidation of that obscurity of the venous circulation, 
on which, he acknowledges, authors have hitherto shed few rays of 
light; to you it is unnecessary to demonstrate that the pressure of the 
atmosphere on the veins external to the cavities must be propagated 
to the termination; that the cavities being always full, there is a con- 
tinued pressure on the vessels within them; add to this the powerful 
dilatation of the heart, auricles and ventricles cooperating in the ac- 
tion, as I have seen them, and you have all the requisites of a pow- 
erful sucking-pump, operating perpetually on the venous system.” 
Dr. Robinson’s surprise that Bichat did not apply the active dias- 
tole of the heart to the “ elucidation of the obscurity,” &c. is easily 
accounted for. Bichat viewed the diastole of the heart in a manner 
very different indeed from Dr. R. Bichat did not believe that the 
auricles and ventricles cooperated in the dilatation of the heart; how 
then could he, indeed, look on the heart as a “powerful sucking-pump, 
operating perpetually on the venous system;” for to act as such, I 
contend the auricles and ventricles should dilate simultaneously; now 
this I also contend they never do. 
I may still further notice the argument of Dr. Robinson in favour 
of his opinions, “founded on the structure of the heart itself.” 
“ Whoever,” he argues, “ inspects with candour and attention the 
structure of the valves, will find it difficult to persuade himself that 13 
they are adequate to the function generally assigned them; he may 
easily ascertain that they offer an impediment to the reflux of the 
blood, but hardly that they afford a complete obstruction; but as the 
contraction of the auricles is less powerful than that of the ventri- 
cles, such reinforcement seems necessary to prevent reflux.” 
I have, nevertheless, examined the hearts of many animals with 
“candour and attention,” and still I cannot persuade myself that 
they are not adequate to the function which the illustrious Harvey 
first assigned them, and which I am satisfied they will be regarded 
as executing by all who examine them. 
The contraction of the auricles always aids in filling the dilating 
ventricles, and is, I think, the principal cause. I admit, of course, 
that atmospheric pressure would cause a fluid to rush through an 
opening into an exhausted vessel; but I cannot, on this account, see 
any good reason why indeed atmospheric pressure, and not the auri- 
cular contraction, should cause blood to pass from the auricles while 
contracting into the ventricles while dilating. The systole of the au- 
ricles is prompt and sufficiently powerful to throw blood into the ven- 
tricles; it commences an instant before the diastole of the ventricles, 
it is in full force when the latter commences; and when the systole 
of the ventricles is in operation, the auriculo-ventricular valves are 
closed, and the diastole of the auricles commences. 
That atmospheric pressure is calculated also to cause blood to en- 
ter the auricles when they are dilating, is what cannot be denied; it 
certainly does not oppose the movement of the blood into the auri- 
cles, but if from other causes the blood move with sufficient velocity, 
as I think it does, why assign an effect entirely to atmospheric pres- 
sure which it only produces in part. 
Structure of the heart.—Believing that the structure of the heart 
must be understood before its action can be explained, I undertook 
to examine it at a time when I was not aware of the exact state of 
knowledge on the subject. After several experiments, I found that the 
sheep’s heart, boiled slowly in a solution of pearl-ash, answered my 
purposes very well. As there is still further room for investigation 
on the subject, I shall give a brief account of the manner in which I 
attempted to unfold the heart. 
On raising a few fibres on the external surface of the heart, I found 
it easy to detach them from the substance of the ventricles, tracing 
them from the base towards the apex. I commenced on the surface 
of the right ventricle, the fibres are all spiral, running from right to 
left over the anterior surface, and back again from left to right on 
the posterior surface, until finally, after two or more turns, they cease 
at the apex; these are the external fibres, which on being raised let 14 
into view those which are below them, and these, gradually, as we 
descend into them, are found to lie more transverse, but still spiral. 
Nothing like a laminated or fasciculated structure is observable, and 
the fibres lie very close to each other. The most superficial fibres 
extend to the apex, the most prominent part of which they constitute? 
those which are next beneath, extend also to the apex, into the com- 
position of which they enter, and so on with others. The external 
fibres, at the very summit of the apex, are continued into the left 
ventricle, and there form the surface immediately under the lining 
membrane? those which I have spoken of as lying beneath the most 
superficial and external, hold the same relative position to the super- 
ficial internal, so that a certain portion of the fibres may be found 
composing the external and internal surfaces of the left ventricle, and 
these fibres, common to both surfaces, are the same and continued. 
Continuing further to unfold the ventricles, it is found that the 
fibres fall short of the apex by degrees as we descend into the struc- 
ture, until finally we find many of them confined to the composition 
of the base. 
In the course of the unravelling, for such it may be fairly called, 
the anterior wall, which is composed of fibres to a great extent com- 
mon to both ventricles, is removed. The right ventricle, however, 
is not composed entirely in this way? there are fibres on its internal 
surface which are common to it and the septum. 
Having arrived at the substance of the left ventricle which is pe- 
culiarly its own, that is, after all the fibres which are common to the 
external part of both ventricles are removed but not broken, it is 
very easy to finish the unfolding, when it will be perceived that all 
the fibres intermediate to those which were first mentioned, after 
winding around twice or more then take a direction upwards, they 
enter into the composition of the columnae carnese. 
We may consider most of the fibres as originating at the base of 
the heart wherever there is cartilaginous matter? but many of the 
fibres arise from the inner surface of the ventricles, and running out 
at the auriculo-ventricular opening become superficial and external 
after having given rounded margins to the cavities from which they 
passed? on the surface they run the course which was first described. 
The termination of the fibres may also, in a great degree, be traced 
to small tendons, or cartilage looking into the cavities, or placed at 
the summit of the septum, where also the auricles are attached. 
As the superficial fibres often wind around the ventricles two or 
three times before their spiral course terminates in that which is 
straight in the cclumnae carneae? so indeed do all the fibres beneath 
them. Suppose a fasciculus of these fibres to extend the course I 15 
have pointed out, then it must be seen that it may be represented by 
a coil of wire, the inner part of which is continued in a straight di- 
rection, and at right angles with the coil5 by depressing the extre- 
mity of this wire, which represents the continuation of the fasciculus 
in the columnse carnese, the coil will be converted into a conical 
spire, perpendicular to which the straight part of the wire still re- 
mains. Suppose another coil, smaller in diameter and similarly form- 
ed, be introduced within the first coil, and its straight wire be de- 
pressed somewhat less than the first, this will represent the next or- 
der of distribution, and so on. Attending to what was said in the 
general description, and retaining this mode of illustration in mind, 
it may be perceived that the ventricles are composed of muscular 
coils, disposed in spiral and somewhat conical form, that the spires 
become shorter as they are less superficial. But as they become less 
superficial, it must be remembered that the inner straight continued 
part of the coils become less perpendicular, and finally, in the most 
deep-seated, it forms a very acute angle instead of the perpendicular 
before described. 
I have not yet obtained results in my experiments on the auricles 
so satisfactory as to induce me to attempt a description of them. 
This however is evident to me, that the fibres of the auricles and 
ventricles are perfectly distinct from one another. In one case out 
of seventeen I found a strong fasciculus of the fibres of the right au- 
ricle perfectly identified with the structure of the ventricles: the con- 
nexion between them was made by a distinct column about three- 
quarters of an inch long. 
We often perceive muscular columns or bands extending from one 
side of a ventricle to the other; I have observed that their direction 
is always oblique, and not directly transverse from one side of the 
cavity to the other, under which circumstance they would greatly 
embarrass the diastole of the heart. These bands do not make it 
more difficult to examine the structure of the heart, as might be at 
first sight supposed. Even the net-work, which the ventricles some- 
times present on their inner surface, will yield satisfactorily if the 
heart be properly prepared. 
I am not prepared to offer an opinion as to the manner in which 
the diastole of the heart is produced. I would therefore merely ask ■ 
is it the consequence of muscular contraction? The only way in 
which I can perceive that the diastole of the ventricles may arise 
from muscu'lar contraction, is that all the fibres of the heart are sti- 
mulated to contract at the same time, but we know that the internal 
surface of the heart is more irritable than the external, and this can 
be proved satisfactorily. It is the muscular fibres of the internal sur- face, then, that are more irritable than the external surface; but it 
has been shown that there is no interruption or separation of conti- 
nuity between the external and the internal muscular fibres. It ap- 
pears from this that one part of a muscular fibre may be more irrita- 
ble than another part. Now, if this be true, it may also be true, that 
one part of a muscular fibre can contract quicker than another part. 
Let us then suppose that the columnse carnese, which constitute but 
a small portion of the entire length of the fibres of the heart, is more 
irritable, and contracts more readily than the spiral part, would the 
ventricles on this account be thrown open suddenly, and closed a lit- 
tle more slowly, by the more gradual and superior power of the spiral 
fibres? * 
I have been to a considerable extent anticipated in my views of 
the structure of the heart by Lower, who published his account of 
it in 1708. 
Influence of respiration and of the active resiliency of the lungs in 
drawing blood into the thorax.—The experiments of Dr. Barry leave 
but little doubt I think, that inspiration, under some circumstances, 
tends to draw blood into the thorax; but I am induced to believe that 
he has greatly overrated the results. My object at present is not to 
analyze Dr. B’s views, but to attempt to show in a few words, how 
far we are to regard atmospheric pressure and the expansion of the 
thorax, as calculated to influence the motion of the blood in the veins. 
Speaking of the powers which circulate the blood in the veins. Dr. 
B. asserts, “ of these powers the pressure of the atmosphere is by far 
the most intense in its degree, the most constant in its influence, and 
the most unvarying in its amount. It is that without which the cir- 
culation could not he maintained beyond a few moments.” We shall 
presently see how Dr. Barry has attempted to verify this assertion, 
with but little success, and how the slightest evidences in its favour 
have been regarded by him as conclusive, while the want of them 
never, for a moment, elicited from him an expression of doubt as to 
the correctness of his doctrine, in the full extent to which he has 
urged it. 
As it at once opens to view the ground-work of Dr. Barry’s theory, 
I quote the following part of his “ argument drawn from anatomy.” 
“ When the chest is enlarged by the act of inspiration, air rushes in 
through the trachea, to distend the air-cells, and force them to oc- 
cupy that space in which the expanding parietes of the thorax tend to 
leave a vacuum. But as it is evident, that the air would follow the ex- 
panding sides of the chest much more readily if there were no cells 
to be distended, and as it is an unalterable law that all liquids in 
communication with an enlarging cavity, will be pressed towards it 17 
if exposed at the same time to atmospheric influence, it became pre- 
sumable that blood would be forced into the thorax through the cavae 
during inspiration. ” 
I make no objection to this argument; it is well known to every 
anatomist how powerfully elastic the substance of the lungs is, con- 
sequently the tendency which it constantly has to collapse, and to 
oppose a distending agent. When the thorax is expanding in inspi- 
ration, it is certainly tending to the production of a vacuum within, 
and the air rushing in through the trachea and its various ramifica- 
tions to fill the vacuum as fast as it is formed, meets a resistance in 
the collapsing power of the lungs; now, as the power of resistance in 
the lungs is something opposed to the expanding power of the thorax 
on the one side, and to the pressure of the atmosphere on the other, 
we at once perceive strong reason to suspect, that all the veins com- 
municating with the cavity of the thorax, and exposed to the influence 
of atmospheric pressure from without, are liable to have the blood 
which they contain pressed into the great venous trunks and the au- 
ricles of the heart when they dilate. 
Dr- Barry’s experiments to prove the production of a tendency to 
a vacuum in the chest during inspiration, I must make known in 
fewer words than he uses. Ist Experiment. A horse was thrown 
upon his right side, left jugular vein exposed, tied below its middle, 
opened an inch below the ligature, a large flexible catheter introduced 
into the open vein and directed towards the heart. To the other ex- 
tremity of the catheter a spiral glass tube was connected, the extre- 
mity introduced into a vessel containing coloured fluid which ascend- 
ed through the tube into the vein, and probably into the heart, during 
inspiration. Blood regurgitated into the tube when the respiration 
was hurried, but returned into the vein at the next inspiration. This 
I call a mere imitation of what we observe in the jugular veins of 
mammalia, and sometimes in the jugular veins of persons in coughing, 
laughing, &c. where the blood is forced into the veins of the neck, 
and drawn back again when inspiration is made. In the report made 
to the “Royal Academy of Sciences, Paris,” upon “Dr. Barry’s 
Memoir,” by Baron Cuvier and Dumeril, the observations of 
Rudiger, Santorini, Haller, Valsalva, Morgagni and M. Ma- 
gendie, on the progression of the blood through the great veins to- 
wards the heart during inspiration are alluded to, not one of whom 
it appears accounts for this phenomenon correctly. To Dr. Barry 
then belongs the credit of having pointed out the mechanism by which 
it is effected, which will be further seen by a short notice of his se- 
cond experiment. 2d Experiment. Two tubes ingeniously contrived 18 
introduced into the cavity of the thorax, one on each side of the pos- 
terior extremity of the sternum, the animal being on its back. The 
other extremities were immersed in coloured liquid. The tubes pe- 
netrating into the cavities of the pleuree made a communication be- 
tween them and the external fluid. The fluid rose rapidly in the 
tubes during inspiration, and was drawn into the chest. I may also 
now give a brief account of Dr. B’s 3d experiment. This was made 
with a view to ascertain whether a tendency to a vacuum was also 
produced in the bag of the pericardium. Having succeeded in intro- 
ducing a tube into this bag, he proved that a fluid ascended through 
it during inspiration. These experiments leave no doubt as to the 
production of a tendency to a vacuum in the cavities now alluded to; 
but while this is admitted as true, it must be acknowledged that the 
power which they exert in drawing to them blood from the veins is a 
subject which still requires to be investigated. Dr. Barry lays an 
estimate on it which no person conversant with anatomy and the phy- 
sical sciences will receive as correct, and while the Baron Cuvier 
and professor Dumeril in reporting on his memoir, speak in the highest 
terms of his experiments, they evidently have not included the 
opinions of Dr. Barry in their commendation. 
In noticing the active resiliency of the lungs, let it not be supposed 
that lam giving my support to Dr. Carson’s doctrine. I believe in 
the active resilience of the lungs, and so does every person who is at 
all conversant with anatomy, but I give but little credit to the fine- 
spun doctrine of Dr. Carson. 
As the lungs are highly elastic and in a forced state of distention 
while they remain sound during the life of an animal, so they have 
a constant tendency to collapse, but in order to do so, they should 
leave a vacuum in the cavities of the pleurae, and also I think in the bag 
of the pericardium. It is very evident they have not the power to 
do so, and they must be regarded therefore at least in the quiescent 
state of the thorax, as leaving no empty space between them and the 
walls of the thorax. The collapsing power of the lungs is considerable, 
but no proper estimate has been made of it; we know how forcibly it 
draws up the diaphragm; it draws, we have reason to believe with 
equal power on the hard thoracic walls all around. Now as there are 
two great cavities separated from one another by the mediastinum, 
it is perfectly in accordance with experience to suppose, that the col- 
lapsing power of the lungs acts with as much power on the medias- 
tinum as on any other surface with which the lungs are in contact. 
But the heart and pericardium are to a great extent concerned in 
opposing the collapsing power of the lungs; the pericardium is also a 19 
sack, and its capacity is not filled by the heart, Dr. Carson therefore 
supposes that the collapsing power of the lungs keeps the pericardium 
in a constant state of extension, and that an antagonizing power to 
the muscular fibres of the heart is thus produced, which operates con- 
stantly to dilate the hearty I certainly cannot agree with the learned 
author of this doctrine, and think he has betrayed great deficiency 
of knowledge in pneumatics in forming it. Had he been better ac- 
quainted with this branch of philosophy, his doctrine would doubt- 
less never have appeared in print. But, let us see in what more 
particularly his error consists. The collapsing power of the lungs is, 
as I have already said, considerable. Dr. Carson made experiments 
to ascertain its amount, and found that it was equal to a column of 
water seven inches high, its ratio then to atmospheric pressure is 
nearly as 1 to 56; its tendency to produce a vacuum is also in the 
same ratio, it cannot therefore with so great a power against it, form 
a vacuum. 
I have not made experiments expressly with a view to measure 
the collapsing power of the lungs in any class of animals, but from 
general observation on the subject, I think the following opinions 
correct. The collapsing power of the lungs increases in an unknown 
ratio as the lungs are inflated from the state of entire collapse, to the 
size which they ordinarily occupy in any animal; beyond this their 
power of resisting a distending power increases in a far greater ratio 
than that before alluded to. The air rushing into the lungs while 
the thorax is expanding, distends the lungs and makes them keep 
pace with the expanding thorax, but when the air does not pass 
through the rima glottidis in volume commensurate with the increase 
of capacity produced in the thorax, then several things are liable to 
happen; there must be left a vacuum in the cavity of the pleurae, or 
the diaphragm must be caused to move upwards to supply the defi- 
ciency of air; or blood in the veins, external to the thorax, must move 
in, or the air in the lungs must expand by its elasticity and dilate 
the lungs. If a very sudden and powerful effort be made to draw in 
air, it is probable, I think, that all of the preceding effects, except 
the first, would follow at the same time, but no one or two would 
subside before the others, they would all be terminated when any 
one of them restored the equilibrium of atmospheric pressure. 
Further, the effect which required the least power to produce it, 
would precede all the others in its extent. Here we want certain 
data, but we may form an opinion as to the forces concerned. Sup- 
pose the resilience of the lungs in such a case to be fifty; expansive 
power of the air three hundred; the latter then would prevail, and 20 
prevent the production of a vacuum from the very commencement. 
The air thus rarified would however only resist external pressure, let 
us suppose as three hundred to three hundred and ninety. The dia- 
phragm would, therefore, be pressed up into the thorax in an arched 
form, the blood would likewise be obliged to rush in, and collect in 
the cavse, so that we should have all these effects produced at once, 
but not a vacuum. Now, suppose a slow inspiration be made, the 
effects, I think, shall be somewhat different from the preceding; the 
entrance of the air into the lungs shall expand them as freely and as 
quickly as the thorax would expand; the diaphragm instead of being 
pressed up, would be forced down, an evidence that the lungs under 
the last condition fill the cavities tightly from the commencement to 
the end of ordinary inspiration. I see no reason then for supposing 
that during ordinary inspiration, blood is moved into the thorax by 
atmospheric pressure. Nor has Dr. Barry ever proved that it does. 
Read his own words. “ The connexion between the motions of the 
liquid in the tube and respiration cannot be satisfactorily observed 
while the horse is standing, because his breathing when in the erect 
posture, and at rest, is scarcely, if at all, perceptible.” The circu- 
lation, however, we must presume, is going on rapidly in every part 
of the body, and according to Dr. Barry, even when a gum elastic 
catheter is introduced through one of the jugular veins, and passed 
almost as far as the superior cava, and through which no water will 
ascend, still Dr. Barry asserts, that atmospheric pressure is more 
powerful than any, or all the other forces in moving the blood through 
the veins. 
“ Here it is essential to remark, that if the communicating tube be 
introduced into the femoral vein of a dog or horse, and pushed no 
further towards the heart, inspiration will produce no effect upon the 
liquid in the cup, because the relative vacuum of the thorax can be 
filled up from the other veins of the animal’s body.” I will merely 
quote another passage from the report of the Baron Cuvier and Du- 
meril on his memoir. 
“Your commissioners, however, must not conceal that in their 
particular opinion the act of inspiration which appears to produce a 
vacuum within the thoracic cavities of animals having lungs, is not 
sufficient to explain the motion of the blood in the veins of fishes, and 
of some reptiles in which the mode of respiration is different.” 
Let any vein, or number of veins be tied as near the heart as is 
possible, it will be found that on puncturing them, a stream of blood 
will issue and continue to flow perhaps as long as there is life in the 21 
animal; or if they be not punctured, it will be found that they become 
full and greatly distended below the ligature, showing conclusively 
that atmospheric pressure is not the great cause of the return of the 
blood from all parts of the system. Even Dr. Carson admitted the 
strength of this objection against the extent to which he felt disposed 
to urge his doctrine. To produce additional proof on this point I 
deem unnecessary. It may be found in Harvey’s valuable work, 
“ De Motu Sanguinis;” Haller’s Physiology; M. Magendie’s Phy- 
siology; Bichat’s Anatomic Generate, and indeed in almost every 
modern work. I can also refer with great pleasure to Arnott’s Ele- 
ments of Physics, second American edition. 
I am now constrained to conclude this paper, in which my sole 
object has been to show the necessity of further investigations re- 
specting the forces by which the blood is moved, and to expose the 
errors of those, as they have appeared to me, who, in their zeal for 
the advancement of medical science, have put forth doctrine upon 
doctrine, hypothesis upon hypothesis, error upon error. 
I cannot but avail myself of the present opportunity to express my 
unfeigned thanks to Dr. Horner, Professor of Anatomy in the Uni- 
versity of Pennsylvania, who has warmly encouraged and aided me 
in my investigations, and directed my attention to various sources of 
information in my inquiry into the state of our knowledge on the sub- 
jects of this paper. To Dr. Isaac Hays, the Editor of the American 
Journal of the Medical Sciences, I am bound to make acknowledg- 
ments for the polite attentions which 1 have received from him, in 
directing my attention to numerous valuable works: but in particu- 
lar, to Dr. Samuel Jackson, Professor of the Institutes of Medicine 
in the University of Pennsylvania, my preceptor and sincere friend, 
under whose auspices I have pursued my studies, and to whom, more 
than to any other person, I am indebted for all that I regard valua- 
ble of what I have acquired in the study of medicine, I avail myself 
of this opportunity to express my gratitude and sense of his exalted 
talents, learning, and above all, of his goodness of heart. 
Philadelphia, April 3d, 1833.