Experimental Researches applied to Physiology and Pathology.
By E. Brown-Sequard, M. D., of Paris.
(Concluded.)
XXXI.—TIIE AUDITIVE NERVE IS A NERVOUS CENTRE.
In an anatomical point of view there is no doubt that the
auditive nerve is a nervous centre. This is proved by the fact
that cells of gray matter are found, not only in the terminal part
of the nerve, but also in its trunk, in many animals, according
to the researches of Stannius, Corti, Kolliker, and myself.
In a physiological point of view, the fact I have discovered,
(see Art. V. p. 21,) viz., that any injury to the acoustic nerve
produces turning, is sufficient to prove that it is a nervous centre.
The degree of pain produced by an excitation of this nervous
centre appears to be as considerable as that caused by a similar
excitation of the trigeminal nerve. I will publish soon an ac-
count of the strange effects produced in different parts of the body
in consequence of an injury of that nervous centre. I will merely
say here that, after such an injury, there are muscles which
appear to be slightly paralyzed. Besides, there seems to be a
notable hypersesthesia of the skin everywhere.
Flourens has found that a section of the semi-circular canals
in birds and some mammals produces a peculiar disorder in the
movements of the head, and, in some cases, turning. He says
that the auditive nerve must be considered as composed, of two
nerves: one going to the semi-circular canals and possessing a
peculiar power on the movements of the body, and the other,
the vestibular or true auditory nerve. What I have found on
frogs is in opposition to these views. A section of the semi-
circular canals, in these amphibia, does not produce any effect
on the movements of the body, and the slightest excitation of
the true auditive nerve is sufficient to produce pain, hyperaesthe-
sia, turning, and other strange effects on many muscles of the
body.
I have sometimes seen turning produced after the mere laying
bare of the kind of bladder, containing the terminal part of the
auditive nerve, in frogs. So slight may be the excitations on
that nerve sufficient to produce turning, that very likely turning
after the laying bare of that bladder was the result of some
slight mechanical injury of the nerve. The rapidity of turning
and the smallness of the circle then described are in proportion
to the degree of injury to the nerve. When the two auditive
nerves are injured, the animal turns on the side most injured.
Sometimes, instead of turning, the animals roll around the longi-
tudinal axis of their body; this takes place in very strong
animals after the terminal part of the nerve has been entirely
crushed.
In frogs deprived of their cerebral lobes, the same effects are
produced after injuries of the auditive nerve, as in unmutilated
frogs.
XXXII.—ON APPARENTLY SPONTANEOUS ACTIONS OF THE CONTRAC-
TILE TISSUES OF THE ANIMAL BODY.
All the contractile tissues of the animal body (the muscles of
the trunk and limbs, the muscular layers of the digestive canal,
the iris, the uterus, the dartos, the cellular tissue, etc.) present,
sometimes, apparently spontaneous contractions. I give this
name to contractions which are not the result of an external
excitation or of an excitation produced by the nervous system on
the contractile tissues. These contractions may be permanent
or momentary, rhythmical or irregular, slight or very powerful.
One of their causes, if not their only cause, appears to be an
excitation directly produced on the contractile fibres by the
carbonic acid existing in the blood.
1.	Contractions in the muscles of the face after a section of the
facial nerve.—My friend Dr. Martin-Magron and myself have
discovered that after the section of one of the facial nerves, on a
rabbit, the face becomes very quickly deviated, not on the healthy
side, as it is known to be in man, but, strange to say, on the
paralysed side. The deviation, very slight at first, increases
gradually during one or two weeks, and then it is so considerable
that the middle of the lips is at a distance of four, five or six
lines from its natural situation. There is an evident state of
contraction in all the paralysed muscles. When the animal is
excited, or when its respiration is somewhat disturbed or pre-
vented, the paralytic muscles tremble, and sometimes they have
rhythmical contractions and relaxations.
The contractions of these muscles may be so considerable that
the bones themselves, and, secondarily, the teeth, may be de-
formed. In one case,^on a rabbit which I had kept living twenty-
one months after the extirpation of one of the facial nerves, not
only the superior and inferior jaws were by far less developed on
the paralysed side than on the other, but the anterior part of
the superior maxillary bone was deviated towards the paralysed
side, so that the middle line of the roof of the mouth was curved
and presented a great concavity on the paralysed side and a cor-
responding convexity on the other.
When the two facial nerves have been divided, there is no
deviation, but there is an evident state of contraction in all the
paralysed muscles, particularly around the lips.*
• Dr. Martin-Magron and myself have found that death occurs from inani-
tion in all the species of mammals on which we have divided the two facial
nerves. After the operation they cannot swallow : we do not know why.
When one of the facial nerves is divided on a dog, on
a cat, or on a guinea pig, there is generally no deviation
on either side. But very frequently there are convulsive move-
ments, and sometimes rhythmical contractions, in the para-
lyzed side of the face. One of these two kinds of movements
always exists in young cats. They are increased, or produced
when they do not exist, in dogs and guinea-pigs, almost every
time we prevent the animal from breathing freely. Once, on a
very vigorous guinea pig, upon which one of the facial nerves
had been torn away, I saw alternate contractions and relaxa-
tions taking place, without a relapse, for eight or ten days after
the operation in the paralysed muscles. After that time, these
tremblings appeared only when the circulation and the respira-
tion were rendered very active, or when the respiration was pre-
vented or diminished. In the case of an impaired respiration,
the strength and frequency of these movements were in propor-
tion to the degree of asphyxia. During many months, the same
phenomena existed in this animal.
I ought to say that in all the experiments above related, the
nerve could not have any share in the movements, because,
the fifth day after the division, or after the extirpation of a
portion of it, the peripheric part had entirely lost its vital
property.
In man, as Dug£s justly remarks, as long as there is no
attempt at movement, voluntary or emotional, the face remains
without any deviation, in cases of facial hemiplegia, which have
not lasted a long time.
2.	On spontaneous rhythmical or irregular contractions in
muscles of animal life, after death—It is a very important fact
in connection with the theory of the action of the heart, as I
will try to prove hereafter, that other muscles, and particularly
muscles of animal life, are capable of having rhythmical move-
ments. This fact I have discovered in the following cases:
a.	After the division of the nerves of the ischiatic and lumbar
plexuses, on one side, in mammals, if we suddenly asphyxiate
the animal, we see, at first, convulsive movements in the three
limbs and in other parts of the body not paralysed. After one,
two or three minutes, these movements cease, and there are only
some tremblings in the muscles of these parts. The paralysed
limb has no movement at all during one or two minutes, after
which time, suddenly, contractions in many bundles of muscular
fibres partially take place. In the same bundle the contractions
sometimes appear to come regularly one after the other. In
some cases I have seen, besides these tremblings, movements of
the entire limb, consisting of some successive flexions and exten-
sions of the limb, and after these movements had ceased, con-
tractions limited to various bundles of fibres appeared. In these
cases the action of the muscles began very late after death, and
once, only six minutes after the beginning of asphyxia, which
lasted two minutes and a half.
b.	Nearly the same movements of which I have spoken as
existing frequently in the face, during life, in rabbits and guinea-
pigs, after the section of the facial nerves, exist always, either
during agony or a little after death. They are generally pro-
duced by partial contractions and relaxations of the different
bundles of fibres of the various muscles. It is rare to see all
the bundles composing one muscle contracting together. These
phenomena last five, six or eight minutes after the last respi-
ration. There are also such movements in the face during agony
and after death, when the nerves have not been cut and when
there is no paralysis; but then the movements appear later and
do not last so long as in paralysed muscles.
c.	I have seen in many rabbits apparently spontaneous rhyth-
mical contractions in the respiratory muscles. In about ten
rabbits, out of forty or fifty, the following phenomena were
very decided; on the others they were slight, and sometimes
very slight, but in all cases a part of them always existed.
I open the abdominal cavity and expose the bowels to the action
of a cold atmosphere, so as to lower the temperature of the
animal; after some minutes I make a little opening in one side
of the chest, and, at last, after a few minutes more, I open
largely one side of the chest. Generally, in such circumstances,
the respiratory movements continue to take place with energy.
I then take away the sternum and divide the two diaphragmatic
nerves. The movement of the diaphragm, nevertheless, continues,
and it exists rhythmically together with the movements of the
other respiratory muscles. Six, eight or ten minutes afterwards
the movements of the diaphragm are still regular, (there are from
five to twenty contractions in a minute;) the intercostal muscles
present then only partial contractions. The different bundles of
fibres of these muscles contract separately one after the other,
but the same bundle has generally regular contractions and re-
luxations. At that time I destroy the spinal cord, and see that
the movements of the diaphragm and of the intercostal muscles
are not changed after this operation ; they last for nearly a quar-
ter of an hour, and in some cases much longer; their regularity
subsists. In the diaphragm, long after the general movement
has stopped, there are regular or irregular contractions of
many bundles of fibres for one, two, three hours, and sometimes
more.
3.	Deviation of limbs produced by a contraction of paralysed
muscles—In pigeons, after the destruction of all the lumbar part
of the spinal cord, the two posterior limbs are completely para-
lysed. The muscles then are soft, and the different parts of the
limbs do not resist at all, when we try to put them in flexion or in
extension. But after a few days the paralysed muscles become
harder, and after a few weeks there is an evident state of con-
traction in them. The limb is generally kept in a state of exten-
sion, and deviated on one side or the other. The deviation
becomes considerable after some months.
Very likely it is owing to the same cause that club-foot and
other deviations are produced in embryos, after a destruction or
an absence of development of the spinal cord.
4.	Rhythmical movements in the eye of the Ink-fish. (Loligo
sepia, L.)—The ciliary muscle so well described by Dr. W. Clay
Wallace, of New York, in the eyes of superior animals, is strongly
developed in the ink-fish. After an eye of this mollusc has been
separated from the body, I have sometimes found very singular
and perfectly rhythmical movements produced by the ciliary
muscle. These movements consisted in alternative contractions
and relaxations of some parts of that muscle. At every contrac-
tion a notable depression was produced in one portion of a zone
corresponding to the circumference of the cornea.* In one case
I have found four times in fifteen minutes the same rhythm ex-
isting in one part of the ciliary muscle. At each of these four
examinations I have found sixteen contractions in one minute.
* The eyes had not been opened.
5. Spontaneous Contractions of the Uterus.—I have seen
hundreds of times the uterus or its cornua, full or empty, contract-
ing to appearance spontaneously, after the death of rabbits and
other animals, at a time when the spinal cord had entirely lost,
not only its reflex power, but also the power of acting on mus-
cles when directly excited by galvanism, by warmth or mechani-
cally.*
*Dr. Tyler Smith, in his very original book on Parturition, (London,
1849, p. 40,) says that “a slow reflex action of the uterus may possibly con-
tinue long after the rhythmic respiratory actions have ceased ; as long, in-
deed, as the bodyretains its warmth.” There is a great error in these lines,
about the relation between the warmth of the body and reflex action. We
may observe reflex actions even in animals that have lost 10, 12 or 15° Cents.,
(18, 22 or 27° Fahr.,) of their temperature, and, in certain circumstances,
these actions may be, then, more powerful than if the temperature of the
body was normal. For instance, if we decapitate an animal after having
put a ligature around the carotid and vertebral arteries, we find, when pul-
monary insufflation is made carefully, that two important phenomena take
place—one is a gradual rapid loss of temperature, if the atmosphere is cold,
(this is the well known fact discovered by Sir B. Brodie,) and the other is a
gradual and considerable increase of the reflex faculty. It has been in
such cases that I have found the greatest degrees of reflex power in mam-
mals. The nervous power accumulates to such an extent in the spinal cord,
that if we pinch the skin in any part of the body, but more particularly on
the chest and on the anterior limbs, a reflex respiratory movement takes
place.
I have also seen movements taking place in the uterus and in
its cornua, in recently dead animals, the spinal cord of which I
had destroyed in all its length. The same movements I have
found after I had taken out from the abdomen of a living animal
the whole uterine apparatus. I have found sometimes that after
I had put a ligature around the trachea of guinea pigs, which
were at the end of gestation, parturition took place and was pro-
duced by three causes: 1st, a direct excitation of the spinal cord
by the venous blood; 2d, a direct excitation of the uterus by that
blood; 3d, a reflex action of the spinal cord. In two cases I
have seen delivery taking place after the action of one only of
these three cases, namely, the direct influence of black blood on
the uterus of the Guinea pigs, the spinal cord of which I had de-
stroyed from the sixth costal vertebra to the sacrum. The more
complete and sudden is the asphyxia, in a rabbit or a Guinea pig,
during labor, the more certain will the delivery take place.
Dr. Tyler Smith speaks of a peristaltic action of the uterus,
which may expel the child -when the mother has died during la-
bor, undelivered. He has not attempted at all to explain that con-
traction, i. e. to find out its cause and the circumstances which
favor or are opposed to its existence ; besides, he has not demon-
strated that the peristaltic contraction is entirely independent of
the nervous system.
6.	Spontaneous rhythmical movements in the crop and oeso-
phagus of pigeons and other birds—I have found that if the crop
of a bird, and more particularly of a pigeon, is opened during
digestion, some rhythmical movements are frequently seen in it
and in the oesophagus. Ordinarily these movements are perfectly
regular. They begin in the upper part of the crop, and are pro-
pagated from there to the oesophagus. If the animal is asphyx-
iated, these contractions become very energetic. Their ordinary
number, in a minute, varies from ten to twenty.
I have ascertained that these rhythmical movements take
place as well in a crop and oesophagus separated from the animal,
as in these same parts left in situ. Therefore, the nervous cen-
tres are not the source from which originates the excitation which
acts on the muscular fibres to put them in contraction.
7.	Spontaneous movements in limbs of persons who have died
of cholera.—It is known that after death by cholera, the whole
body, and more particularly the limbs, have sometimes very con-
siderable movements. In some cases I have seen alternative
movements of flexion and extension of the arms or of the legs,
even three hours after the cessation of the beatings of the heart.
Physicians who know how quickly after death the nervous system
loses its vital powers, will admit easily that these movements can-
not be the result of an action of that system. I have ascertained
on more than sixty bodies of men who died of cholera, or of
various other diseases, that a short time before, or a very short
time after the cessation of the beatings of the heart, no reflex
action was produced by the tickling of the sole of the foot. The
greatest duration of reflex action that I have observed after death
has been in a case of cerebral apoplexy. It has lasted thirteen
minutes after the last breathing, and about eight minutes aftei’
the last beating of the heart. Dr. Bennet Dowler has recorded
many curious facts (observed in cases of death from yellow-fever,
cholera, etc.,) from which he concludes also that the movements
taking place in the limbs are not reflex actions.
I have found that, in general, the more sudden and complete
has been the asphyxia before death, by cholera, the more the
limbs are moved after death. I have found also that it is in pa-
tients who have died during the algid period that these move-
ments are ordinarily found.
These facts, as I will show hereafter, appear to prove that
these movements, like the other movements, of which I have
previously spoken, are excited by carbonic acid alone, or toge-
ther with the poison of cholera.
8.	Spontaneous contractions of the bowels, the bladder, the iris
and other parts of the body.—It is known that frequently at the
time of death, many of the contractile tissues of the body are
put into contraction. I can go farther and say that it is so with
all the contractile tissues; and that, contrary to the general
opinion, a nervous action is not necessary for these contractions.
There are contractions in all the following organs or tissues
during agony and after death : 1, the muscles of animal life ;
2, the sphincter of the anus ; 3, the respiratory muscles; 4, the
iris ; 5, the digestive canal (in all its length); 6, the urinary
bladder; 7, the uterus; 8, the scrotum, (dartos); 9, the gall-
bladder; 10, the ureters; 11, the seminal vesicles; 12, the
bronchial tubes; 13, the skin; 14, the blood-vessels; 15, the
lymphatics ; 16, the cilia.
As to the skin, in many cases the so-called goose-flesh (cutis
anserina) takes place a little before or little after death, although
the body has not yet become cold. I have seen it very strongly
marked on the inferior limbs of a paraplegic who died of a soften-
ing of the dorso-lumbar part of the spinal cord. It results from
this fact that the cellular tissue is able to contract from the same
cause which produces contractions at the time of death, in mus-
cular tissues—that is, very likely, carbonic acid.*
* Kolliker has recently discovered fibro-muscular cells—that is, mus-
cular fibres of organic life—in the skin, and he maintains that the cutis
anserina is produced by these fibres, and not by the cellular fibres. I have
published facts which, I think, prove conclusively that the contractions in
the skin are in a great measure performed by the cellular tissue. fSee
Comptes Rendus de la Soc. de Biologie, 1849, t. i. pp. 134 et 157, et 1850,
t. ii. p. 132.) Since that time, I have found that in some cartilaginous
fisheB, in which the iris does not contain any muscular fibre, and is com-
posed of cellular tissue, this membrane may be the seat of considerable
contractions ; so that I consider it as perfectly certain that the cellular tissue
(at least in some organs) is contractile.
Besides, I have found contractions of the cellular tissue of the
skin of the face, in animals killed by asphyxia, and on which the
facial nerve had been divided for many days or weeks.
In the same man who had a paraplegia, and of whom I have
just spoken, I saw very strong contractions in the dartos, during
agony.
In animals suddenly asphyxiated, after the destruction of the
dorso-lumbar part of the spinal cord, the seminal vesicles some-
times contract, and a slow ejaculation takes place, although there
is no erection.
In the sphincter of the anus, when it is paralysed, there are
only slight contractions, but they are evident.
The urinary bladder, during agony or after death, sometimes
contracts so much, even when it is paralysed, that all the urine
it contains is expelled.
The ureters present very strong contractions, in animals
recently killed by asphyxia, and these contractions in some cases
are rhythmical. The same movements are seen when all the
urinary apparatus is in situ, and when it has been removed from
the abdomen, and therefore separated from the nervous centres.
The contraction begins at the kidney and thence is very quickly
propagated all along the ureters to their termination in the blad-
der. Among the contractile tissues, that of the ureters is one
of the most irritable.
Bidder and Schmidt, of Dorpat, have recently found that after
the division of the two pneumogastric nerves, there is more car-
bonic acid expelled by the lungs than usual. This fact is very
important, because if the theory, which I am about to propose,
be true, we ought to see a contraction produced in the bronchial
tubes, in consequence of the unusual amount of carbonic acid
that they contain. Now, such a contraction certainly exists then,
and it is it which causes the well-known difficulty in the expan-
sion of the chest, which exists in that case.
In the eyes, even when they are paralysed by the section of
the three nerves of the iris, (the third pair, the sympathetic, in
the neck, and the ophthalmic nerve,) the pupil may, at first, con-
tract and afterwards dilate very much.
The lymphatics and the thoracic duct contract very much after
death. I have, sometimes, in cases where these vessels were
dilated by chyle, introduced a glass tube, two lines in diameter,
into the thoracic duct, and I have seen the liquid ascend into the
tube, and in one case run out, although the tube was five inches
high.
The cilia are known to have movements independent of the
nervous system.
The gall-bladder contracts little and slowly, but evidently,
after death, even when it has been, with the liver, removed from
the abdomen and separated from the nervous centres.
The choledoch duct and the pancreatic duct, as my fr-iend Cl.
Bernard has discovered, have rhythmical contractions during life,
in birds. I have found these movements perfectly regular after
I had removed all the viscera from the abdomen. Therefore the
cause of these rhythmical contractions is not in the nervous
centres.
The bowels have considerable contractions during agony and
after death; and I will prove hereafter that the cause of these
movements is not the influence of cold, or that of air, when they
are exposed to the atmosphere. Nurses, in France, are in the
habit of judging that death has positively taken place, when,
after the cessation of breathing, they see urine and faecal matters
expelled. This expulsion depends upon the contractions then
taking place in the bladder and in the bowels.
9.	Causes of the apparently spontaneous contractions during
life and after death.—All the contractions of which I have
spoken, appear to me to be produced by an excitation made upon
the contractile tissues by a substance existing in the blood, and
the quantity of which becomes much increased during asphyxia.
The relations between these contractions and asphyxia are evi-
dent. A great many of them do not exist unless asphyxia
exists, and their energy is always in proportion to the degree of
asphyxia.
I believe that the substance in the blood which has that power
is the carbonic acid. In admitting this opinion we can easily
explain all the phenomena.
There are certain contractions which take place in muscles of
animal life, after death, and which have quite another cause. In
the cold seasons, it is not uncommon to find, in limbs of frogs,
when we separate them from the body, apparently spontaneous
contractions, lasting sometimes for half an hour or even more ;
but these contractions have begun when we have cut the nerves,
and they continue on account of galvanic discharges which ac-
company them. The fact that they begin after the excitation of
a nerve, is sufficient to show that they are not like the other con-
tractions, of which I have previously spoken.
Some of the facts I have related may appear to be distinct
from the others. So, for instance, contraction taking place in
paralysed muscles of the face or of the limbs in living animals,
might be considered as quite different from the contractions exist-
ing after death. I think that they originate from the same cause,
viz., an excitation by carbonic acid. A muscle may be moved
or not be moved by an excitant. If the degree of irritability is
greater in one case than in another, we may see the same amount
of excitation produce a movement in the first case, and not in the
second. If the amount of excitation increases, then we may see
both muscles moved, but the most irritable more than the other.
This is sufficient to explain why the paralysed muscles may be
moved by the carbonic acid existing in the blood during life,
while the muscles that are not paralysed are not moved. I have
found that the degree of irritability increases, during a certain
time after paralysis, in the muscles of animal life. Their irrita-
bility being augmented, they are excited sufficiently to contract,
by a quantity of carbonic acid which is not sufficient to act on
the other muscles.
The following facts and reasonings will, I believe, prove that,
at least in the bowels, black blood, very likely by its carbonic
acid, may excite powerful movements. It is known that when
we open the abdomen of an animal immediately, or a short time,
after death, we generally see considerable movements in the
bowels. These movements have been attributed to the action of
air, or to that of cold, on the bowels. This is not a right view.
A sudden exposure to a cold atmosphere may, possibly, produce
contractions in the bowels; but certainly cold is not the ordinary
cause of these movements. At first, they may exist in a warm
atmosphere, and then they appear to be more rapid than in a
cold atmosphere. Besides, the bowels may be exposed to a cold
atmosphere, and remain motionless, although they have their en-
tire irritability. As to atmospheric air, it is not able to excite a
movement in the bowels. If we open the abdomen of a living
animal, in avoiding to excite mechanically the bowels, and in al-
lowing the animal to breathe freely, we may for a long time see
no other movement in the bowels, except, sometimes, slight re-
gular and natural peristaltic motions, depending on digestion,
and limited to some small parts of the bowels. The animal must
be kept on his back, and we must avoid touching the bowels, be-
cause a slight contact is sufficient to produce movement. Now,
if we prevent the animal from breathing, we see, after ten, fif-
teen, or twenty seconds, very violent, sudden, and rapid contrac-
tions taking place in all parts of the intestine, from the stomach
to the rectum, but much more in the small intestine than else-
where. These movements are quite different from the digestive
peristaltic movements. If the animal is allowed to breathe again,
and freely, the movements diminish gradually, and disappear
almost entirely after a few minutes. Then, if we prevent it
again to breathe, we see the movements produced again. This
experiment may be repeated many times, with the same result,
on the same animal.
We are certainly entitled to conclude that there is an exciting
cause of contractions, developed during asphyxia, and that it is
neither the cold nor the atmospheric air which produces in all
cases the movements of the bowels after the opening of the abdo-
men. We may draw the same conclusions from another experi-
ment. If we put a tie around the trachea of a living animal,
immediately after expiration, we may see and feel violent move-
ments taking place in the bowels, although the abdomen is not
opened. It is in consequence of such movements that there is
an expulsion of faecal matters, after death, in man. The urine
may be also expelled in these cases, in man and in animals, and
this expulsion takes place because the bladder contracts, and not,
as it is generally admitted, because the sphincter vesicce becomes
relaxed.
Some physiologists have considered the cessation of the circula-
tion of the blood in the bowels as the cause of their movements,
after death, and they relate as a proof the fact that the section of
one of the arteries going to a part of the intestines, is followed by
contractions in the parts thus deprived of circulation. But no-
thing is explained by saying that the cause of the contraction is
in the absence of circulation. As contractions require an exci-
tation to be produced, what is the exciting cause when the blood
doesnot circulate? After the section of an artery there is blood
remainingin the capillaries, and that blood, after a short time, be-
comes very rich in carbonic acid, and then, if my theory is right,
contractions ought to be produced. The result of the section of
one of the arteries is, therefore, in accordance with my theory.
Other facts may be adduced proving the influence of black
blood and carbonic acid on the bowels.
If black blood is injected in the arteries of the small intestine
when its irritability is much diminished, movements are almost
immediately produced, but they do not last long. On the con-
trary, if red blood is injected, movements do not appear immedi-
ately, and they are very strong and last long. This action of
red blood may be easily understood: it increases the irritability
of the muscular layer of the bowels, as it does for that of the
muscles of animal life, and when it has been changed into black
blood, it excites the muscular tissue and produces contraction.
The strength and the long duration of the contraction in this
case depend on the increase of irritability. When, as in the
above experiment, black blood (containing a great quantity of
carbonic acid, on account of the constant formation of that gas
in blood deprived of the contact of atmospheric air) is injected,
the irritability is not sensibly increased, but the excitation is con-
siderable and there is an almost immediate effect.
If air is injected in the arteries of the bowels, soon after the
death of the animal, a part of the blood it contains is expelled,
and we find that the movements do not last as long as if the
blood had not been removed.
When an animal is killed by haemorrhage, the intestine, as well
as all the other organs, contains more blood than usual, and then
its movements are not so strong, and last less than they do gene-
rally.
When in a recently asphyxiated animal the arteries and veins
of a part of the bowels are divided, the movements of that part
become less strong and last less than those of the other parts of
the intestine.
When the bowels of a recently asphyxiated animal are put
under a receiver containing carbonic acid, their movements are
very much increased, but they do not last so long as when they
are in the atmosphere.
When they are put under a receiver containing hydrogen,
their movements are very quickly diminished in strength, and
they last still less than when exposed to carbonic acid.
When they are put in oxygen, their movements diminish a
little at first and soon after become stronger, and they last much
longer than usual.
As a general conclusion about the apparently spontaneous con-
tractions which I have described as taking place in paralyzed
muscles during life or after death, I will say that it seems that
black blood by its carbonic acid is the cause of these contractions.
When the nervous centres are still united with the contractile
tissues, we see, during agony or after death, stronger movements
generally than when they are separated. The action of black
blood on the nervous centres may be very great. I have found
that the spinal cord, when separated from the encephalon, may
be strongly excited by black blood. If an animal is asphyxiated
after a transversal and complete division of its spinal marrow in
the dorsal region, we see convulsions taking place in the poste-
rior limbs, and they are nearly as strong as when the nervous
centers have not been injured. The excitation on the spinal
marrow is considerable enough to produce an erection of the
penis.*
* Almost all, if not all, the secretions of the body are increased during
asphyxia: bile, (as shown by Professor Bouisson,) saliva, tears, gastric,
pancreatic and intestinal juices, and also liver-sugar, etc., are produced in
greater quantity then than usual. I believe that this increase results from
the excitation of the nervous system, and, in some measure, perhaps, from
a direct action of black blood on the capillaries of the glands. The urinary
secretion may also be changed in asphyxia, and not only then the urine
may contain sugar, as Alvaro Reynoso has found, but also albumen.
XXXIV____ON THE CAUSE OF TnE BEATINGS OF THE HEART.
The cause of the rhythmical movements of the heart has been
heretofore unknown. I believe I have discovered it.
Before exposing my theory and the facts upon which it is
grounded, I will show that the theories put forward until now
are not correct.
There are three theories only which are worthy of examina-
tion: 1st, that of Haller; 2d, that of Carpenter; 3d, that of
Budge, Schiff, and others.
Haller has been very near the truth in admitting that the
beatings of the heart were excited by the blood. His error has
been an error loci. He thought that the blood acted in the
cavities of the heart. It is not so; and it is known that the
heart may continue to beat after all the blood has been drawn
out of its cavities.
The doctrine of Carpenter* is a very simple and remarkable
one. He believes that the muscular fibres may act without hav-
ing been excited. A muscle, says he, may be compared to the
electric jar, and become so charged with motility, (or motor force,)
as to execute spontaneous contractions ; and elsewhere, “ It is not
very difficult to conceive that the ordinary rhythmical movements
of the heart may be due to a simple excess of this motility, which
is continually being supplied by the nutritive operations, and is
as constantly discharging itself in contractile action.” Carpenter
believes that the reason for which the heart presents spontaneous
contractions while the other muscles do not, (at least ordinarily,)
is, that there is a higher degree of motility in the heart. He
considers as very important the facts I have discovered, that
many other muscles besides the heart may present rhythmical
movements. He thinks that these facts show there is a tendency
to rhythmical movements in the muscles themselves, altogether
independent of the excitement to action which they receive
through the nervous system.
* See his Principles of Human Physiology, American edition, by F. G.
Smith. Philadelphia, 1853. pp. 130 to 132, 319, 325, and 471-72.
The best ground for the hypothesis of Carpenter is that, ac-
cording to him, the heart continues to beat, although it is not
exposed to any excitation in certain circumstances. He says:
“ When every source of excitement is excluded, we cannot but
perceive that these actions take place with a spontaniety which
can scarcely be accounted for in any other way than by con-
sidering them as expressions of the vital activity of the compo-
nent cells of these forms of muscular tissue, which manifests it-
self in this mode, when the developmental life of the cell has at-
tained its maturity. And this view is strikingly confirmed by
what we know of the origin and termination of these movements.
For the action of the heart commences when, as yet, its contrac-
tile parietes consist but of an assemblage of ordinary-looking
cells, no proper muscular tissue being evolved, and no nervous
system being yet developed, from which the stimulus to the move-
ment can proceed; and it is impossible to assign any other cause
for the movement under such circumstances, than the attributes
inherent in the tissues which perform it.”
The first thing to be said against the view of Carpenter is, that
his hypothesis is not necessary; because it is possible to assign
another cause for the movement of the heart under the circum-
stances he speaks of. This will be proved hereafter.
The doctrine of Carpenter implies, that the degree of irrita-
bility (motility, motor force, contractility,—never mind the
name) is greater in the heart than in the other muscles which
have no spontaneous action. This is not the case. The degree
of irritability, as judged by its duration after death, is generally
greater in the muscle of animal life, than in the heart. The ac-
cepted sentence of Haller, Cor ultimum moriens, generally, is
not true.
If Carpenter was right, we should see, during life, the appa-
rently spontaneous contractions which take place in all the con-
tractile tissues after death; because their irritability is at a
higher degree in the first, than in the second case. Besides, we
should not see oxygen, or red blood, diminish the frequency of
the beatings of the heart; and black blood, or carbonic acid, in-
crease that frequency.
An experiment, consisting in the research of the influence of
vacuo on the heart, has been made by Tiedemann and by Dr.
S. W. Mitchell, and Dr. T. II. Bache, (see Dunglison’s Physiol.,
vol. ii. p. 150.) It seems to me that the result of this experi-
ment is in complete opposition to the doctrine of Carpenter.
These experimenters have found that the beatings of a heart were
speedily brought to a stand by the exhaustion of the air, and
that they w’ere renewed when it was re-admitted. If the view
of the eminent British physiologist was right, we ought to see
the heart continue to beat in vacuo about the same length of time
as it -would in hydrogen or nitrogen, because its irritability
cannot be suddenly diminished enough by the exhaustion of the
air. In these gases the heart of a mammal may beat for five or
ten minutes or more, and the right auricle may beat for hours ;
and the heart of a frog may beat for one day. It is much more
to account for the stopping of the heart’s action in admitting that
the excitant of that action is removed during the exhaustion of
the air. John Reid had found that the heart of a frog had con-
tinued to beat in vacuo, but how long he does not say.*
* Art. Heart, in Todd’s Cyclop., vol. ii. p. 611. J. Reid says in the same
page, “We ought to be more cautious in admitting the existence of this in-
nate moving power, since it is in opposition to a well known law in the
animal economy, that though the various tissues of an organised body are
endowed with certain vital properties, yet the application of certain exter-
nal and internal stimuli is necessary to produce their manifestations of
activity. In fact it is from the action and reaction of these tissues and
excitants upon each other that the phenomena of life result.”
I will relate hereafter many experiments of mine which are in
opposition to the theory of Carpenter.
It is one of the most important questions in physiology, whether
the nervous centres, the nerves, and the contractile tissues are
able to act without stimulation. This question has not been
yet entirely treated by any physiologist. I propose publishing
a special paper on the subject. I will merely say here that there
may be apparently spontaneous actions in the spinal cord, as well
as in the muscles. For instance, very frequently, in a frog, after
the removal of the brain and the medulla oblongata, we may see
strong movements apparently spontaneous, but when we know
that the slightest excitation of the skin, or of any other very sen-
sitive part, may excite the spinal cord, and produce a reflex ac-
tion, we are authorised to consider all the movements taking place
as reflex actions. An excitation may have come to the spinal
marrow from the bladder, from the bowels, from the lungs, (in
which worms are almost always found in the cold seasons, i. e.
at the time these phenomena are generally observed,) etc.
As to the spontaneity of action in muscles, I have tried to
prove ia a preceding article that it is a mere and false appear-
ance. t I will prove hereafter that the cause of the apparently
j" Carpenter says that the action of the uterus, as it showsitself, “not
merely in the final parturient effort, but in local contractions that frequently
occur during the latter months of gestation, (simulating the movements of
the foetus,) are more satisfactorily accounted for by considering them as a
discharge of accumulated power, than in any other mode.” I will try to
spontaneous contractions of the heart, is the same as that of the
like contractions in other contractile tissues.
The physiologists who maintain that the beatings of the heart
depend on the nervous system, appear to me to be greatly mis-
taken. They make a confusion between two things, greatly dis-
tinct, one from the other: they conclude from the fact that the
nervous system is able to act on the heart, that its influence is
necessary. It is the same kind of mistake which is so frequently
made as to the influence of the nervous system on nutrition, on
secretions, and on animal heat; because that system is able to
act upon these functions, it is concluded that its influence is ne-
cessary.
The first argument to be adduced against the writers who ad-
mit, as necessary, the influence of the nervous system on the
heart, is, that they change only the ground of the difficulty in
doing so. Instead of having to explain why the heart acts rhyth-
prove elsewhere that for the uterus, as well as for any other contractile
tisue, there is no spontaneous action. The uterus, in pregnancy, becomes
more and more irritable every day, and when its irritability has arrived at
a very high degree, then the slight excitation produced by the carbonic
acid normally contained in the blood is sufficient to put it in action. When
the contractions have begun, they are very much increased by a reflex ac-
tion. Every contraction is accompanied by a galvanic discharge on the
nerves in the neighborhood of the muscular fibres which contract, and the
sensitive nerves being thus excited, it results, 1st, that a pain is felt, the
degree of which is in proportion to the degree of any contraction, and
therefore with the degree of galvanic discharge;* 2d, that the spinal mar-
row is excited, and produces reflex movements in the uterus. Now, the
more these reflex contractions are energetic, the more they are induced to
take place again, on account of the galvanic discharge which accompanies
them. So that there would be a constant increase in the intensity of the
contractions if there were not four limits to them. 1st, there is no
galvanic discharge when the muscular fibres are contracted; it is only
at the time they are contracting that this discharge takes place; 2d, the
primitive cause of contraction, the excitation of the muscular tissue, by car-
bonic acid, diminishes much during the contraction, because the caliber of
the small blood-vessels is much diminished, and the blood expelled from
them ; 3d, every contraction of the uterus diminishes the degree of its irri-
tability ; 4th, the reflex power of the spinal cord becomes exhausted, or at
least diminished.
* See, on this subject, my paper in the Comptes rendus de la fociete de Bologne, en. 1850, t. ii.
p. 172.
mically, they have to explain why the nervous system acts rhyth-
mically on the heart. Not only they have not explained this
rhythmic action of the nervous system, but, as far as I know,
they appear not to have been aware that this was to be explained.
The second reason I will mention, is the fact, so well esta-
blised by my friend Professor Lebert, that, in embryos, the heart
beats when it is merely composed of cells, and when the nervous
system has not yet appeared,
A third reason is, that, either in monsters, or in animals ope-
rated on by physiologists, there has been a long persistence of the
beatings of the heart when a part of the cerebro-spinal centre did
not exist, or had been removed. Any part may be in that case,
even the medulla oblongata, as I have discovered. (See Art. xvi.
p. 40.)
In opposition to the idea that the beatings of the heart depend
on the microscopical ganglia existing in that organ, I will say,
that, besides the fact that the heart beats in embryos before the
nervous system exists, and besides the improbability that such a
small amount of nervous matter should have so great a power,
there are two good reasons against this strange theory:—
1.	There have been found no ganglia, large or microscopical, in
the auricles, in the sinuses of the pulmonary veins, or in those
veins. All these parts, nevertheless, may continue to beat a long
while, (even for hours,) after they have been separated from the
ventricles where are the microscopic ganglia. 2. Rhythmical
movements may exist in a great many other muscular parts of the
body, where there is no microscopical ganglion, and where these
parts have ceased to be under the influence of the nervous centres.
The three theories which I have examined being unable to ex-
plain the beatings of the heart, I will now expose my theory,
and discuss the three following questions :—1. What is the exci-
tant which puts the heart in action ?	2. Does that excitant act
rhythmically ?	3. Does th,at excitant act together directly on
the muscular fibres of the heart, and on the nervous system; or
does it act only on the muscular fibres ?
After having solved these three questions, I will examine the
objections which might be made to the doctrine I propose.
1. What is the excitant which puts the heart in action?
I believe that the beatings of the heart are excited by a prin-
ciple existing in the blood, and that carbonic acid is that princi-
ple. This view is grounded on the following facts:
a.	When we prevent a warm blooded animal from breathing, the
beatings of the heart become more frequent than before, for about
one or two minutes. It is not on account of the emotion alone
that it is so, because the same effect is produced when we as-
phyxiate suddenly an animal which has entirely lost his power
of having emotions, in consequence of the action of chloroform.
b.	Many times I have found, on myself and on one of my
friends, that the beatings of the heart are rendered more active
during asphyxia. We hold our breath for about three quar-
ters of a minute, and during the last fifteen seconds the heart
beats from two to four (in one case five) minutes more than when
the respiration was free. We have made the experiment in the
sitting position, avoiding any movement of the body in all the
cases.
c.	John Reid has discovered that when any hemadynamometer is
put in the femoral artery of a dog, the mercury rises in the in-
strument if the animal is asphyxiated, and about one minute after
the respiration has been stopped. The same result has been ob-
tained in twenty experiments. It seems to me that this fact
proves that the contractions of the heart become more energetic
during asphyxia. John Reid attributes the result he has obtained
to some difficulty that black blood seems to have in passing through
the capillaries of the different parts of the body. I do not deny
that there is such a difficulty; but I think that the great reason
of the ascension of mercury in the hemadynamometer is, the in-
crease in the force of the heart. A simple experiment proves
that I am right. I adapt the hemadynamometer to the aorta in
the abdominal cavity, and then I open quickly the chest, and I
put a ligature to the brachial and carotid arteries. About three
quarters of a minute after opening the chest, and about half
a minute after the ligature has been put on the arteries of the
head and arms, the mercury rises notably in the instrument;
sometimes the elevation is as considerable as two inches. It re-
sults from this experiment, that the heart beats more strongly in
asphyxia about one minute after its beginning.
d.	Woodall, a most intelligent and accurate observer, says Dr.
Martin Paine, (see Med. and Physiol. Comment., t. ii. p. 49,)
states, that the best remedy for syncope is to obstruct respiration
entirely by momentarily confining the nose and mouth. If this
be true, it is in perfect accordance with my view, that, during as-
phyxia, the normal cause of the beating of the heart increases in
the blood.
e.	If a frog is put under a receiver containing pure oxygen, at
a temperature of 40 or 50° Fahr. (4, 5, or 10 Cent.) after its
heart has been laid bare and its central nervous system destroyed,
we see the heart beat for a very long time, (one, two, or three
days.) On the contrary, if, at the same temperature, another
frog, deprived also of the central nervous system, is put in car-
bonic acid gas, the heart beats very quickly at first, but it soon
ceases to beat, (in one or two hours only, sometimes, and for the
most about half a day.)
f.	All the causes which increase the formation of carbonic acid
gas in the body, increases the frequency of beatings of the heart.
g.	If we inject the serum of blood into the arteries of the heart,
so as to expel as completely as possible the blood contained in the
capillaries of this organ, and if then we remove the blood from
the cavities of the heart, we find that its beatings are, at once,
almost entirely suspended, and that they are completely stopped
in a very short time, (from one to eight minutes.) The muscu-
lar irritability is not destroyed in this organ; it does not beat
because its excitant has been removed.
h.	I have found that when the heart of a young animal is put
in hydrogen, its beatings hardly change at first, but they stop in
a very short time. When it is put in carbonic acid gas, its beat-
ings are, at first, increased in frequency and strength; but they
very soon are stopped. When it is put in oxygen, its beatings
are slowly increased in frequency and strength, and they last
very long.
i.	On newly-born cats and dogs, before the occlusion of the
ductus arteriosus, I open the chest and put a ligature on the ar-
teries going to the head and fore limbs, and on the aorta imme-
diately after the origin of the ductus arteriosus. Then the blood,
expelled from the right ventricle, is sent to the lungs, from which
it comes to the left auricle, and afterwards to the left ventricle.
From there it is sent into the only part of the aorta remaining ac-
cessible, and thence it goes into the cardiac arteries, and into the
pulmonary artery, through the cluctus arteriosus, (a direction which
is the reverse of the normal direction in that duct.) By the cardiac
veins the blood arrives again in the right side of the heart. The
circulation from the heart to the lungs, and vice versa, continues
very well. I have found, that if hydrogen is insufflated into the
lungs, the beatings of the heart arc not much c.hanged at first,
but they go on diminishing, and they disappear in a short time.
When an injection is made with carbonic acid, the beatings of the
heart are quickly increased in frequency and strength ; but they
are stopped after a short time. When oxygen is insufflated, the
beatings of the heart become slowly more frequent, and they re-
main quick and strong for a long time. (I have once, by such
insufflation of oxygen, maintained beating for eleven hours in the
heart of a young cat.)
I believe that these facts prove that black blood, by its car-
bonic acid, is an excitant of the beatings of the heart. If, now,
we adduce to these facts all those I have related in a preceding
article, on the apparently spontaneous contractions in all the
contractile tissues of the body, we shall have a very considerable
number of facts, proving that, during asphyxia, there is an ac-
cumulation in the blood of the principle which causes these con-
tractions. I believe that it is almost impossible to deny that this
principle is the carbonic acid gas.
Before trying to show that what takes place in asphyxia in
the heart is only an exaggeration of what normally exists in that
organ, I will treat the two remaining of the three questions I
have announced I would endeavor to solve, as regards the exci-
tant of the heart’s action.
2.	Why does that excitant act rhythmically ?
I believe it is easy to explain why the agent of excitation of
the heart* produces rhythmical contractions. I will suppose, first,
that the action is permanent. A part of the heart, ventricles, or
auricles, being dilated, receives an excitation in all its fibres si-
multaneously, and a contraction is produced. But, according to
the well-known law of Schwann, the exciting cause which is able
to give the impulse when the muscular fibres are long, is not able
* What I will say here for the heart, might be said for all the contractile
tissues, presenting apparently spontaneous rhythmical contractions, as the
cilia, for instance.
to maintain the contraction when the fibres have been shortened.
Then, on account of this insufficiency of power of the cause of the
contraction, a dilatation ensues. We may present the fact in
other words, and say that the resistance to the contraction origi-
nating from the displacement of the constitutive matter of the
contractile tissues, increases in proportion to the shortening of
the fibres; and that after the fibres have contracted under the
impulse of the exciting cause, although this cause continues to
act, a dilatation is produced by the force belonging to that re-
sistance, which is nothing but elasticity. If the cause of the con-
traction of the heart was a considerable one, then we should see
a permanent contraction ; and it is so when we apply galvanism—■
the elasticity, then, is not powerful enough to produce dilatation.
On the contrary, with a weak exciting cause, like carbonic acid,
the result ought to be different. When that cause has more
power, as in asphyxia, the shortening of the fibres takes place
quicker, and is more considerable; and even then it is not suffi-
cient to maintain contraction, the tendency to dilatation being
also increased.
I ought to say, that the excitant cause of the contractions is
not always at the same degree of power. The small blood-vessels
and the capillaries being compressed during the muscular con-
tractions, there is a diminution of excitation during that time.
This should be sufficient to explain the alternate contractions
and dilatations. But such a diminution in the caliber ought to
be very little, if even it exists in certain organs, (the heart when
composed of cells, for instance.)
I come now to the third question about the excitant of the
heart—
3.	Does that excitant act together on the muscular fibres and
on the nerves of the heart, or does it act only on the muscular
fibres ?
I believe it ought to act also on the nerves ; but I cannot prove
it otherwise than by saying, that all the agents of excitation that
we know to act on the muscular fibres, are able to act on the
nerves.
There are many things to be said besides the above facts and
reasoning, to prove the truth of the doctrine I propose. I will
expose some of them.
The following question might be made:
How is it that the heart is the only muscle containing striated
fibres, which presents normally rhythmical movements ?
The answer to this question appears to be very simple. The
intensity of the stimuli, the degree of irritability, and the resist-
ance which a muscle has to overcome when it contracts, are three
elements which we ought not to lose sight of when we examine
the difference of contractions between two muscles. Suppose the
heart possessing the same degree of irritability as another mus-
cle : if the stimulus is the same, and the resistance the same also,
for the heart and for the other muscle, there will be the same
effects. But if the stimulus is more considerable in the heart
than in the other muscle, and if the resistance to be overcome is
less for the heart, then with the same degree of irritability in
both parts, and even with less irritability in the heart than in the
other muscle, we will see a movement in the heart, and not in
that other muscle. Now a simple examination of the vessels of
the heart, proves that they contain more blood, and consequently
more stimulus, than the other striated muscles. Besides, as the
heart is not inserted into heavy bones to be moved, it has less re-
sistance to overcome when it has not to circulate the blood, as
after death, or when it is out of the chest, than the muscles of
animal life. Some muscles in the face and the diaphragm, being
almost without an external resistance, when their contractions
do not go so far, it results that they are moved much more easily
after death, than the muscles of the limbs. In consequence of
these views, I believe that, although there is in the blood-vessels
of all the muscles of the body a principle which is an exciting
cause of contractions, there are no contractions produced, be-
cause the quantity of that principle is not sufficient, or because
the resistance to contractions in many muscles is greater than in
the heart.
I must, in conclusion, say, that I do not advance my theory of
the rhythmical movements as perfectly proved. I believe it is
true, and that there are a great many facts which appear posi-
tively to prove it. What I can assert is, that it is by far much
more in harmony with all the known facts, than the other theories.