CONVERSION OF NERVE FORCE INTO HEAT. By Surgeon H.
A. Chatham Gray,
M.B., Edinburgh.
The conversion of nerve energy into thermal energy is not a new idea. Although it has not been demonstrated by experimental
yet many physiologists believe that this does place in the animal economy ; and enters as a factor in the production of animal heat. I am a firm disciple of those who believe " that the production of heat is essentially dependant upon nervous agency, of
really
physiology,
take
which it i3
one
of the manifestations."
Carpenter, in his "Principles of Human writes:?" On the other hand, from the close relation which exists between the vital and the physical forces, it can scarcely
Physiology,''
Dr.
regarded as improbable that the nervous force, generated by changes in the nervous substance, may manifest itself under the form of heat, just as we know that it manifests itself (in the electric fishes, &c.,) under that of electricity, and thus it is quite conceivable, that one mode in which alimentary materials may be applied to the maintenance of animal heat, may consist in their subservience to these molecular changes, which seem to take place in the nervous substance with more activity than any other tissue ; and thus a large measure of caloric may be generated through the immediate instrumentality of the nervous system, notwithstanding that the ultimate source of its development lies (as in the chemical theory) in the oxidation, of the elements of the food. Such an hypothesis will be found consistent, the author believes, with all the well-ascertained
be
molecular
facts of the case, &c." This view is based
on some physiological and pathological phenomena that cannot be accounted for by Profes30r Liebig'a chemical theory of animal heat. In the present paper I wish to sum up very briefly the
reasons that seem to me to warrant such an idea. These reasons may be classified into physical, physiological, and pathological. Physical.?"Without the aid of physics, physiology could not
advance; for that science gives
us the means by which we elicit nature. Now physics has worked out for us these grand truths: that the universe is composed of particles of matter, which we call at our option atoms or molecules ; that these molecules manifest certain properties by the particular
the secrets cf
organic
modes of motion they assume; that these modes of motion affect other modes of motion in fluids (as air and water) which are the media of so much motion in the world; that the mole-
cules and their modes of motion can
be no motion without the
are inseparable, i.e., that there molecules; that analogy warrants
in assuming that every molecule is in a constant state of motion?motion of some kind or another according to the peculiar nature of the molecule; and that one mode of motion can, under favourable conditions, be changed into another mode of motion. This is the doctrine of the correlation of forces. From the above it will be evident that the properties of the great of objects around us are but kinds and degrees of us
variety
motion; and that for us to take cognizance of them our senses must conduct these modes of motion modified in various ways to the organ of cognition?the brain?in which these modes of motion undergo some mysterious changes, and perception, thought, volition, &c., are the result. Thus the optic nerve conducts that mode of motion we call light; the nerve that mode of
auditory
motion called sound, the gustatory taste, and so on. Hence it is certain that all nerves transmit modes of motion ; and these modes of motion undergo various changes according to the requirements of the case. Sensory nerves conduct motion centripetally; motor nerves centrifugally, motion i3
Centripetal
THE INDIAN MEDIC ALfi GAZETTE.
238
changed in the nerve centres into centrifugal motion, produces muscular action, &c. Though one mode of motion has disappeared, yet it is not lost; it has passed into another mode of motion. The doctrine of the conversion of forces must hold good. often
?which
It is not the intention of this paper to enter into the nature of the force that is converted into nerve force (though it seems that this is chemical); nor the various forces into which nerve
is changed. This I shall take up, if I am permitted, in another paper; and I shall be able to shew that vision, hearing, taste, smell, &c. result from the perception of waves of motion. We are now concerned with heat alone.
force
temperature whicli lasts for some hours. Sir B. Brodie records a in which the cord was severely injured in the cervical region: all the nerves proceeding from below the seat of injury were completely paralysefl; yet the heat in the groin was 1110 F. How are such cases to be explained ? the complete paralysis of the nerves below the injury proves that volitional power only was lost. Nervous force mu3t have been still conducted by those nerves, and a larger amount, too, than usual, for the injury causing irritation at the upper part of the cord must have genei-ated more nervous influence, which for some time after the injury was being converted into heat.
If the cord has been very severely injured, the high temcannot last long, but if the injury is slight just enough to cause inflammation or irritation, tho temperature will, in all
perature
increase in temperature?nearly l-3rd of a degree Fahrenheit in the muscles of a frog. Then again, why does the temperature rise higher when the muscle is prevented from contracting f I think the answer is easy. The nerve force brought by the nerve to the muscle causes the latter to contract, i.e., the
correctly the sympathetic are paralysed. The same thing occurs " blushing,", in which a
invisible nerve motion is changed into the visible muscular motion ; but the whole of the nerve motion is not so transformed, a portion appears as thermal motion, which becomes dissipated At the same time it must be granted that the chemical action in the muscle contributed something towards the production of heat. Moreover, Ileidenhain's observation further proves this theory. For, why has the muscle that is prevented from
a higher temperature than that which is allowed contract? If it be not due to the fact that the nerve fries ?which should have produced muscular motion is connected iuto heat, to what else can it be attributed ? A certain amount of motion must result in an equivalent motion, therefore a certain amount (say x + y) of nerve force must result in a: amount of muscular motion, and y amount of heat; or (if the muscular
shortening to
motion is prevented) in x + y amount of heat. Sir B. Brodie shewed experimentally that, when the brain is severed from the spinal cord, or when its functions are suspended by means of a narcotic, the temperature of the
body
falls rapidly; but the fall is less rapid if artificial respiration is performed. This seems to shew that the removal of nervous centres, which originate nerve force, tends to lower, the heat-producing " capacity of the body. Dr. Cnrpenter says that the subsequent and Chossat are LeGallois M. M. of experiments decidedly confirmatory of this conclusion, whilst they extend it to other lesions of the nervous centres, the influence of which upon the calorific function appears to be proportional to their severity."
Division of cerebro-spinal nerves causes a fall of temperature in the parts supplied by them. Thus Mr. Nunn records a case of division of the ulnar in which the nerve in a
boy,
of the hand fell to 10? F. below that of tho sound This result is the antithesis of that M. produced
temperature Bide.
Claude Bernard by division of the cervical sympathetic. Now there are a few cases in which severe
by
injuries of the system produce a rise of temperature. Many experimenters have noticed that one of the first effects ef division of the spinal cord in the back is uu elevation of
nervous
1875.
case
Now to the physiological facts. It is said that animal heat is almost wholly produced by the chemical changes which the food and tissues undergo. "We must admit that chemical action is at the bottom of all vital processes, but with how much reason could we say that all the animal heat ia the result of direct chemical action ? If it were proved that chemical action originates nerve force, and that nerve force produces heat, it would surely not be right to affirm that the chemical change is the cause of heat. It certainly is the indirect cause of heat; but the nerve force is the direct cause. Helmholtz has shewn by the thermo-electric apparatus that during action the temperature of a muscle rises ; and Heidenhnin has demonstrated that the temperature is higher when the muscle is prevented from shortening than when it is permitted to do so. How are we to explain these phenomena? In the first place?why does the temperature of the muscle rise ? Can it be due solely to the more vigorous chemical changes taking place in the muscle ? Surely not; for there is a considerable
[September 1,
continue till the nervous structure has returned to its normal condition. Such cases have been of late pretty
probability,
recorded in " The Lancet," tho most remarkable of which is that published by Mr. J. W. Teale, in which after injury to tho spine the temperature rose to 122? F. These
frequently
cases
would more
correctly
come-under the head of
pathological.
M. Claude Bernard demonstrated that division of the cervical sympathetic nerve of one side caused a very great rise of
temperature on the same side of the face. The temperature rises even higher when the superior cervical ganglion is removed. This condition lasts for many months, and does not seem to be due to any pathological changes going on in the tissues; for in M. Bernard's experiments no oedema nor any other morbid phenomenon resembling inflammation was
observed.
We know that tho va?o-motor nerves or nerves
in the
proper?the
more
fibres of Remak?
physiological phenomenon
sensation of heat is felt.
In this
of
case
the emotion evolves an unusual amount of nerve force, which passing along cerebro-spinal nerves disturbs the inhibitory action of the nerves of Remak ; tho balance of nerve motion is thus destroyed, and tho superabundant nerve force is connected into
From the experiments of various physiologists we heat. know :? 1 st.?That the motor fibres of the sympathetic system arc concerned in secretion, &c., i.e., in tho molecular motions of the tissues. 2nd.?That tho sensory fibres of the sympathetic system give a vital sense to the tissues, a sense akin to muscular sense. 3rd.?That the fibres of Remak, the sympathetic fibres proper, regulate tho calibre of tho blood vessels, keeping them in a normal state of tension. Now with these data how can we account
for tho rise of
temperature after paralysis of tho sympathetic ? It is shewn by experiment, that tho motor fibres and the fibres of Remak carry nervous influence to tho tissues supplied by them, while the sensory fibres carry nervous energy from those tissues, that is, the two former sets of fibres conduct nerve motion cenirifugally, and tho latter set centripetally. Thus two forces meet in the tissues, tho ono carrying on tho secretions and excretions, &c., and the other regulating theso processes by means of its power over tho vascular system. When these two forces aro in normal balance, tho tissues are healthy ; when the nerve motion in tho motor fibres is greater than normal, it tends to overcome the opposing motion brought by the fibres of Remak, thus paralysing their function ; and tha inhibitory action being destroyed, tho unopposed nervo motion brought by tho motor fibres becomes converted into heat. Pathological facts, too, tond to confirm tho belief resulting from the above physiological phenomena. All acute inflammations of tho brain and spinal cord, whether traumatic or idiopathic, are accompauied with a high tomperftture.
It is
quite
evident that when neryoua tissue becomes
inflated*
September 1,
1875.]
AN OUTBREAK OP CHOLERA IN ROORKEE.?BY A. ETESON.
move nervous force must be generated; it is this nerve force that is converted into heat. In the slow, degenerative diseases of the nervous system, ?which produce paralyses, we generally find a temperature below normal. In these cases the nervous centre has undergone mole-
and is, therefore, redered incapable of generating force which should go to the production of heat. In tetanus the temperature is high, and this because a large amount of nervous force is liberated. Some of this puts the cular
that
change,
nervous
muscles into tetanic spasms; the rest is changed into heat. In " The Lancet" of March 10th may be seen a letter on high temperature. The writer, after saying something regarding Mr. Teale's case, writes :?" So-called hysterical patients appear in way to possess a power (however unconsciously it may of generating heat at the spot to which at the time their attention is directed." Now if this observation be how is it to be explained ? I know of no better some
be
exercised)
correct,
tion than the
one
some other motion; then becomes of it ?
in
explana-
for nerve motion must result and if it does not result in heat, what
I have
given;
I have now given very briefly the facts supporting the theory of the conversion of nerve energy into thermal energy. All we now require is physical demonstration, and this will form the 1 think that any one with time and most important proof. at his disposal can soon settle the matter. A. very delicate thermo-electric apparatus would take cognizance of variations of temperature that may be suddenly produced by irritating nerve centres and nerve trunks. The whole theory might fall to the ground, but I am very sanguine that it will
opportunities
stand the ordeal of demonstration. One objection has been brought against this theory, this is that vegetables generate heat; they have no nervous system; therefore the heat in animals cannot be dependant on the nervous
system.
The
absurdity
of the argument is so
I shall not pursue the subject any further. Calcutta, \%th June 1875.
evident, that
239
A. Chatham Gray,
M.B., Edinburgh.
The conversion of nerve energy into thermal energy is not a new idea. Although it has not been demonstrated by experimental
yet many physiologists believe that this does place in the animal economy ; and enters as a factor in the production of animal heat. I am a firm disciple of those who believe " that the production of heat is essentially dependant upon nervous agency, of
really
physiology,
take
which it i3
one
of the manifestations."
Carpenter, in his "Principles of Human writes:?" On the other hand, from the close relation which exists between the vital and the physical forces, it can scarcely
Physiology,''
Dr.
regarded as improbable that the nervous force, generated by changes in the nervous substance, may manifest itself under the form of heat, just as we know that it manifests itself (in the electric fishes, &c.,) under that of electricity, and thus it is quite conceivable, that one mode in which alimentary materials may be applied to the maintenance of animal heat, may consist in their subservience to these molecular changes, which seem to take place in the nervous substance with more activity than any other tissue ; and thus a large measure of caloric may be generated through the immediate instrumentality of the nervous system, notwithstanding that the ultimate source of its development lies (as in the chemical theory) in the oxidation, of the elements of the food. Such an hypothesis will be found consistent, the author believes, with all the well-ascertained
be
molecular
facts of the case, &c." This view is based
on some physiological and pathological phenomena that cannot be accounted for by Profes30r Liebig'a chemical theory of animal heat. In the present paper I wish to sum up very briefly the
reasons that seem to me to warrant such an idea. These reasons may be classified into physical, physiological, and pathological. Physical.?"Without the aid of physics, physiology could not
advance; for that science gives
us the means by which we elicit nature. Now physics has worked out for us these grand truths: that the universe is composed of particles of matter, which we call at our option atoms or molecules ; that these molecules manifest certain properties by the particular
the secrets cf
organic
modes of motion they assume; that these modes of motion affect other modes of motion in fluids (as air and water) which are the media of so much motion in the world; that the mole-
cules and their modes of motion can
be no motion without the
are inseparable, i.e., that there molecules; that analogy warrants
in assuming that every molecule is in a constant state of motion?motion of some kind or another according to the peculiar nature of the molecule; and that one mode of motion can, under favourable conditions, be changed into another mode of motion. This is the doctrine of the correlation of forces. From the above it will be evident that the properties of the great of objects around us are but kinds and degrees of us
variety
motion; and that for us to take cognizance of them our senses must conduct these modes of motion modified in various ways to the organ of cognition?the brain?in which these modes of motion undergo some mysterious changes, and perception, thought, volition, &c., are the result. Thus the optic nerve conducts that mode of motion we call light; the nerve that mode of
auditory
motion called sound, the gustatory taste, and so on. Hence it is certain that all nerves transmit modes of motion ; and these modes of motion undergo various changes according to the requirements of the case. Sensory nerves conduct motion centripetally; motor nerves centrifugally, motion i3
Centripetal
THE INDIAN MEDIC ALfi GAZETTE.
238
changed in the nerve centres into centrifugal motion, produces muscular action, &c. Though one mode of motion has disappeared, yet it is not lost; it has passed into another mode of motion. The doctrine of the conversion of forces must hold good. often
?which
It is not the intention of this paper to enter into the nature of the force that is converted into nerve force (though it seems that this is chemical); nor the various forces into which nerve
is changed. This I shall take up, if I am permitted, in another paper; and I shall be able to shew that vision, hearing, taste, smell, &c. result from the perception of waves of motion. We are now concerned with heat alone.
force
temperature whicli lasts for some hours. Sir B. Brodie records a in which the cord was severely injured in the cervical region: all the nerves proceeding from below the seat of injury were completely paralysefl; yet the heat in the groin was 1110 F. How are such cases to be explained ? the complete paralysis of the nerves below the injury proves that volitional power only was lost. Nervous force mu3t have been still conducted by those nerves, and a larger amount, too, than usual, for the injury causing irritation at the upper part of the cord must have genei-ated more nervous influence, which for some time after the injury was being converted into heat.
If the cord has been very severely injured, the high temcannot last long, but if the injury is slight just enough to cause inflammation or irritation, tho temperature will, in all
perature
increase in temperature?nearly l-3rd of a degree Fahrenheit in the muscles of a frog. Then again, why does the temperature rise higher when the muscle is prevented from contracting f I think the answer is easy. The nerve force brought by the nerve to the muscle causes the latter to contract, i.e., the
correctly the sympathetic are paralysed. The same thing occurs " blushing,", in which a
invisible nerve motion is changed into the visible muscular motion ; but the whole of the nerve motion is not so transformed, a portion appears as thermal motion, which becomes dissipated At the same time it must be granted that the chemical action in the muscle contributed something towards the production of heat. Moreover, Ileidenhain's observation further proves this theory. For, why has the muscle that is prevented from
a higher temperature than that which is allowed contract? If it be not due to the fact that the nerve fries ?which should have produced muscular motion is connected iuto heat, to what else can it be attributed ? A certain amount of motion must result in an equivalent motion, therefore a certain amount (say x + y) of nerve force must result in a: amount of muscular motion, and y amount of heat; or (if the muscular
shortening to
motion is prevented) in x + y amount of heat. Sir B. Brodie shewed experimentally that, when the brain is severed from the spinal cord, or when its functions are suspended by means of a narcotic, the temperature of the
body
falls rapidly; but the fall is less rapid if artificial respiration is performed. This seems to shew that the removal of nervous centres, which originate nerve force, tends to lower, the heat-producing " capacity of the body. Dr. Cnrpenter says that the subsequent and Chossat are LeGallois M. M. of experiments decidedly confirmatory of this conclusion, whilst they extend it to other lesions of the nervous centres, the influence of which upon the calorific function appears to be proportional to their severity."
Division of cerebro-spinal nerves causes a fall of temperature in the parts supplied by them. Thus Mr. Nunn records a case of division of the ulnar in which the nerve in a
boy,
of the hand fell to 10? F. below that of tho sound This result is the antithesis of that M. produced
temperature Bide.
Claude Bernard by division of the cervical sympathetic. Now there are a few cases in which severe
by
injuries of the system produce a rise of temperature. Many experimenters have noticed that one of the first effects ef division of the spinal cord in the back is uu elevation of
nervous
1875.
case
Now to the physiological facts. It is said that animal heat is almost wholly produced by the chemical changes which the food and tissues undergo. "We must admit that chemical action is at the bottom of all vital processes, but with how much reason could we say that all the animal heat ia the result of direct chemical action ? If it were proved that chemical action originates nerve force, and that nerve force produces heat, it would surely not be right to affirm that the chemical change is the cause of heat. It certainly is the indirect cause of heat; but the nerve force is the direct cause. Helmholtz has shewn by the thermo-electric apparatus that during action the temperature of a muscle rises ; and Heidenhnin has demonstrated that the temperature is higher when the muscle is prevented from shortening than when it is permitted to do so. How are we to explain these phenomena? In the first place?why does the temperature of the muscle rise ? Can it be due solely to the more vigorous chemical changes taking place in the muscle ? Surely not; for there is a considerable
[September 1,
continue till the nervous structure has returned to its normal condition. Such cases have been of late pretty
probability,
recorded in " The Lancet," tho most remarkable of which is that published by Mr. J. W. Teale, in which after injury to tho spine the temperature rose to 122? F. These
frequently
cases
would more
correctly
come-under the head of
pathological.
M. Claude Bernard demonstrated that division of the cervical sympathetic nerve of one side caused a very great rise of
temperature on the same side of the face. The temperature rises even higher when the superior cervical ganglion is removed. This condition lasts for many months, and does not seem to be due to any pathological changes going on in the tissues; for in M. Bernard's experiments no oedema nor any other morbid phenomenon resembling inflammation was
observed.
We know that tho va?o-motor nerves or nerves
in the
proper?the
more
fibres of Remak?
physiological phenomenon
sensation of heat is felt.
In this
of
case
the emotion evolves an unusual amount of nerve force, which passing along cerebro-spinal nerves disturbs the inhibitory action of the nerves of Remak ; tho balance of nerve motion is thus destroyed, and tho superabundant nerve force is connected into
From the experiments of various physiologists we heat. know :? 1 st.?That the motor fibres of the sympathetic system arc concerned in secretion, &c., i.e., in tho molecular motions of the tissues. 2nd.?That tho sensory fibres of the sympathetic system give a vital sense to the tissues, a sense akin to muscular sense. 3rd.?That the fibres of Remak, the sympathetic fibres proper, regulate tho calibre of tho blood vessels, keeping them in a normal state of tension. Now with these data how can we account
for tho rise of
temperature after paralysis of tho sympathetic ? It is shewn by experiment, that tho motor fibres and the fibres of Remak carry nervous influence to tho tissues supplied by them, while the sensory fibres carry nervous energy from those tissues, that is, the two former sets of fibres conduct nerve motion cenirifugally, and tho latter set centripetally. Thus two forces meet in the tissues, tho ono carrying on tho secretions and excretions, &c., and the other regulating theso processes by means of its power over tho vascular system. When these two forces aro in normal balance, tho tissues are healthy ; when the nerve motion in tho motor fibres is greater than normal, it tends to overcome the opposing motion brought by the fibres of Remak, thus paralysing their function ; and tha inhibitory action being destroyed, tho unopposed nervo motion brought by tho motor fibres becomes converted into heat. Pathological facts, too, tond to confirm tho belief resulting from the above physiological phenomena. All acute inflammations of tho brain and spinal cord, whether traumatic or idiopathic, are accompauied with a high tomperftture.
It is
quite
evident that when neryoua tissue becomes
inflated*
September 1,
1875.]
AN OUTBREAK OP CHOLERA IN ROORKEE.?BY A. ETESON.
move nervous force must be generated; it is this nerve force that is converted into heat. In the slow, degenerative diseases of the nervous system, ?which produce paralyses, we generally find a temperature below normal. In these cases the nervous centre has undergone mole-
and is, therefore, redered incapable of generating force which should go to the production of heat. In tetanus the temperature is high, and this because a large amount of nervous force is liberated. Some of this puts the cular
that
change,
nervous
muscles into tetanic spasms; the rest is changed into heat. In " The Lancet" of March 10th may be seen a letter on high temperature. The writer, after saying something regarding Mr. Teale's case, writes :?" So-called hysterical patients appear in way to possess a power (however unconsciously it may of generating heat at the spot to which at the time their attention is directed." Now if this observation be how is it to be explained ? I know of no better some
be
exercised)
correct,
tion than the
one
some other motion; then becomes of it ?
in
explana-
for nerve motion must result and if it does not result in heat, what
I have
given;
I have now given very briefly the facts supporting the theory of the conversion of nerve energy into thermal energy. All we now require is physical demonstration, and this will form the 1 think that any one with time and most important proof. at his disposal can soon settle the matter. A. very delicate thermo-electric apparatus would take cognizance of variations of temperature that may be suddenly produced by irritating nerve centres and nerve trunks. The whole theory might fall to the ground, but I am very sanguine that it will
opportunities
stand the ordeal of demonstration. One objection has been brought against this theory, this is that vegetables generate heat; they have no nervous system; therefore the heat in animals cannot be dependant on the nervous
system.
The
absurdity
of the argument is so
I shall not pursue the subject any further. Calcutta, \%th June 1875.
evident, that
239
