FOOTNOTES:

FOOTNOTES:[56]It is not true that a ligature on a nerve produces its effects only on the part to which this nerve is distributed; the brain is also affected; for, without this, how can be explained the pain that is felt, and the excitement, which is often sufficiently powerful to produce convulsions, and sometimes even death.[57]The facts related here by Bichat are not conformable to those, which, the philosophers and physiologists have observed who have been more particularly engaged with this kind of experiments. Besides the consequences which he has drawn from them are not accurate, and he seems to be ignorant what course the galvanic fluid in this case takes.[58]If there is always a relation between the vital energy of the brain and its alternate motions, it is because there is a constant relation between these motions and the entrance of the blood into the organ. Thus then, instead of considering this shock as the exciting cause of the brain is it not more natural to see in it only an effect purely accidental of the arrival of the arterial blood, which every thing proves to be the real excitant?[59]As we know absolutely nothing of the manner in which the intellectual phenomena are produced in the brain, we cannot say whether compression prevents their development by stopping the motions with which the brain is habitually agitated, or by preventing the entrance of the arterial blood, or finally in some other way that we do not suspect.[60]The organization of these animals differs too much from that of man to enable us to draw conclusions from one to the other, especially in what concerns the functions of the nervous system. There is an experiment of M. Dumeril in which a salamander lived a long time after the amputation of the head, till the formation of a perfect cicatrix in the neck, which intercepted the passage of air to the lungs.[61]Why are not the cerebral functions disturbed, when water is pushed slowly into the carotids? because there is then mixed with the blood of the artery too small a quantity of water at a time to enable this fluid to have a very evident action on the brain. But if this introduction of water into the mass of blood continues, whatever precaution may be taken, its effects soon show themselves. We have often, in our experiments, introduced a great quantity of water into the veins of an animal, and though much of it passed off by pulmonary transpiration, the arterial blood soon became very aqueous. Now, we have always observed, that in this case, the animals were struck with a kind of stupidity, which evidently indicated a want of action of the brain.[62]It is not uncommon to see patients, who retain their intellectual faculties perfectly, when the motions of the heart are so feeble, that they certainly cannot produce, in the mass of brain, any sensible jar.[63]A very considerable quantity of air can be forced into the veins of an animal, without causing its death, provided it be not pushed in suddenly. In all these cases, it is understood, that the quantity that can be thus introduced is in proportion to the size of the animal. I have before me at this moment the details of an experiment that I made on a horse at Alfort with M. Dupui, and in which, before the animal died, I was able, in thirty seven minutes, to inject quickly into the veins forty syringes full of air, and three syringes full into the carotid artery. (The capacity of the syringe was seventeen centilitres.) The animal died three minutes after the last injection. At the examination of the body, we found air in the azygos vein and in the thoracic duct, which contained much lymph, as well as the lymphatic vessels of the internal surface of the lungs. The heart was enormously distended with air mixed with a small quantity of blood.[64]This is not correct, and death takes place, on the contrary, by the cessation of the motions of the heart. The right ventricle is filled with air; and this air, dilated by heat, so distends it, that it can no longer contract.[65]The disorders which are produced in this case do not at all resemble those which follow the entrance of air into the veins. If we push towards the brain, by the carotid artery, a small quantity of air, we see almost immediately signs of a strong cerebral congestion, spasmodic stiffness of the muscles, loss of sensibility, and of the action of the senses, and all the phenomena of a real apoplexy. Respiration and the circulation go on some time without any apparent alteration, but finally these two functions become embarrassed and the animal sinks. Every thing leads to the belief, that the alteration in the circulation of the brain depends here on the presence of rarefied air in the ultimate arterial ramifications.When apoplexy is thus produced by the injection of air, if it be still forced into the artery, it breaks open violently a passage for itself, it tears the small vessels, and spreads in the parenchyma of the brain, which it makes emphysematous and crepitating under the finger. There finally returns a portion of it by the veins, which goes to the right cavities of the heart and which contributes to arrest the circulation.[66]In the two examinations related by Morgagni, it appears that after a sudden death, there was found in the vessels of the brain an aeriform fluid, to the presence of which, for the want of another material cause, was attributed the death of the individual; but there is no proof that this fluid might not be developed there after death. We shall now relate a more decided case of death occasioned by the presence of air in the blood vessels; but here there is no ground for doubt, because we know the circumstances of the introduction.A locksmith, twenty three years of age, had had for five years a large tumour on the right shoulder and clavicle. His acute sufferings induced him to enter the hospital to have it removed.It was necessary in the operation to remove the middle portion of the clavicle. Thus far the success was complete; but little blood was lost, the pulse was good and the breathing easy, when the patient suddenly cried out,My blood is leaving my body! I am dead!And at the same moment he became stiff, lost his consciousness, and was covered with a cold sweat. A singular and rather loud noise was heard in the interior of his chest. The surgeon thought that he had opened the pleura by removing a portion of the clavicle, and thus given access to the air and to the blood to the right side of the thorax. The fingers of an assistant were immediately thrust into the bottom of the wound, with the view of stopping the supposed opening in the pleura, and the surgeon endeavoured to introduce into the thorax the extremity of a sound of gum elastic. When he thought that he had succeeded, he drew with his mouth the air which he supposed to be effused in the pleura. He wished then to proceed to the dressing; and, in order to do this, he substituted, for the fingers of the pupil which were at the bottom of the wound, a sponge covered with wax; but the moment the sponge took the place of the fingers, the same noise that was at first heard and which had ceased in an instant, was renewed with more force than before.The syncope and cold sweat still continued. Water thrown into his face, made him give some signs of life; but he died a quarter of an hour after the appearance of the accident I have just described, and forty five minutes after the commencement of the operation.The body was examined the next morning. They expected to find the right pleura open, much blood and air effused into its cavity and the lungs on that side collapsed. Nothing of the kind was found. The pleura was whole and there was no effusion in it. The lungs were as usual; but an opening of half an inch in extent was discovered in the external jugular vein, at the place where this vein opens into the subclavian. The cavities of the heart were large but contained no blood. Bubbles of air were observed in the vessels of the brain; the other vessels were not examined.This fact was related to me the same day, by a student who was present. It was impossible for me not to refer the death in this instance to the entrance of air into the vessels. The opening in the vein, the noise that was heard, the suddenness of the death, the absence of blood in the cavities of the heart, the presence of air in the vessels of the brain, all sufficiently indicated it. I suspected that the entrance of air had been favoured by the state of tension of the parietes of the vein, or by their morbid alteration, which did not allow them to flatten by atmospheric pressure. I thought that this phenomenon might be produced at will on animals by placing them in the same physical circumstances. I introduced then into the jugular vein of a dog, a sound of gum elastic, and I directed it towards the heart. It was hardly there before I heard the air enter the vein, and the animal fell down in syncope, with the peculiar noise which manifests the presence of air in the heart. I immediately closed the sound to prevent the entrance of more air, and the animal gradually recovered, because the quantity of air introduced had not been in sufficient quantity to produce its death. I then opened the sound, and immediately the air rushed in towards the heart, and its entrance was followed by the same consequences; but, whether from not closing the sound soon enough, or from the entrance of a greater quantity of air, the animal died unexpectedly to me. In opening it, I found all the signs of death from the sudden entrance of air. The right ventricle was distended with air mixed with a little blood.Sometimes, without any apparent alteration in the texture of the veins, its parietes do not flatten under atmospheric pressure; a simple puncture then is sufficient, as in bleeding, to admit the air into the vessels. Lieutaud relates two cases in which it appears that this took place, and several veterinary surgeons have assured me that they have heard, after bleeding in the jugular vein, a noise which indicates the entrance of air. Usually the quantity introduced is too inconsiderable to produce any evident effects. There has been communicated to me, however, a case observed by Mr. Bouley, the younger a veterinary surgeon in Paris, in which the entrance of air was followed by effects similar to those which we have related.Mery had long since observed, that, in opening the abdomen of a dog, and puncturing the vena cava above the origin of the emulgents, as the vein become emptied of blood, it filled with air, which went to the right ventricle. Haller also observed that air entered into the veins of frogs and other cold-blooded animals in consequence of a wound of some large vessel. He has shown that it was from this source that was derived that which Redi, Caldesi, and Morgagni saw circulating in the vessels of these animals, since it is not observed, when the necessary precautions are taken to prevent its introduction.Nysten has made a great number of experiments upon the injection of elastic fluids into the veins, and the results which he has obtained accord perfectly with those which we have observed. He is not satisfied with injecting atmospheric air, he has introduced in the same way a great number of other gases. He has remarked, that among the gases not deleterious he can introduce, without causing death, a much greater quantity if these gases are easily dissolved in the blood.We cannot follow him in the detail of these experiments; we shall only relate a result relative to the colouring of the blood in the lungs. He has observed, that by injecting air into the vein, so slow as not to produce the death of the animal, the colouring of the arterial blood is rendered imperfect. He is satisfied, he says, that it is not owing to the embarrassment of the lungs. The injection of oxygen does not alter this colouring. The injection of azote completely prevents it; that of the oxide of carbon does not produce any change in it. I give these results from his work; I have not had occasion to verify them myself.[67]When air is introduced into the vena portæ, there is not only no ill effect at the moment of injection, but there usually follows no apparent effect on the animal. It is not the same when air is injected into the veins of the general system, with so much care as not to produce instantaneous death by the dilatation of the heart. The effects do not then appear till a long time after the injection; but they are wholly different from the primary effects which we have described.These consecutive symptoms from the entrance of air into the veins are, as Nysten has remarked, the result of an obstruction of the lungs produced by the accumulation of air in the last divisions of the pulmonary artery. The embarrassment in respiration often appears at the end of half a day, it becomes greater and greater, the bronchiæ are filled with a viscid fluid; and the animal usually dies on the third or fourth day. On examination of the body, no air is found in the heart or the vessels; but the lungs, instead of being pink-coloured, are greyish, tinged with brown, and loaded with frothy blood and mucus.Boerhaave thought, that death which follows the injection of air into the veins was always owing, as it is in this case, to the presence of the air, which offers, in the small vessels, a mechanical obstacle to the passage of the venous blood.

[56]It is not true that a ligature on a nerve produces its effects only on the part to which this nerve is distributed; the brain is also affected; for, without this, how can be explained the pain that is felt, and the excitement, which is often sufficiently powerful to produce convulsions, and sometimes even death.

[57]The facts related here by Bichat are not conformable to those, which, the philosophers and physiologists have observed who have been more particularly engaged with this kind of experiments. Besides the consequences which he has drawn from them are not accurate, and he seems to be ignorant what course the galvanic fluid in this case takes.

[58]If there is always a relation between the vital energy of the brain and its alternate motions, it is because there is a constant relation between these motions and the entrance of the blood into the organ. Thus then, instead of considering this shock as the exciting cause of the brain is it not more natural to see in it only an effect purely accidental of the arrival of the arterial blood, which every thing proves to be the real excitant?

[59]As we know absolutely nothing of the manner in which the intellectual phenomena are produced in the brain, we cannot say whether compression prevents their development by stopping the motions with which the brain is habitually agitated, or by preventing the entrance of the arterial blood, or finally in some other way that we do not suspect.

[60]The organization of these animals differs too much from that of man to enable us to draw conclusions from one to the other, especially in what concerns the functions of the nervous system. There is an experiment of M. Dumeril in which a salamander lived a long time after the amputation of the head, till the formation of a perfect cicatrix in the neck, which intercepted the passage of air to the lungs.

[61]Why are not the cerebral functions disturbed, when water is pushed slowly into the carotids? because there is then mixed with the blood of the artery too small a quantity of water at a time to enable this fluid to have a very evident action on the brain. But if this introduction of water into the mass of blood continues, whatever precaution may be taken, its effects soon show themselves. We have often, in our experiments, introduced a great quantity of water into the veins of an animal, and though much of it passed off by pulmonary transpiration, the arterial blood soon became very aqueous. Now, we have always observed, that in this case, the animals were struck with a kind of stupidity, which evidently indicated a want of action of the brain.

[62]It is not uncommon to see patients, who retain their intellectual faculties perfectly, when the motions of the heart are so feeble, that they certainly cannot produce, in the mass of brain, any sensible jar.

[63]A very considerable quantity of air can be forced into the veins of an animal, without causing its death, provided it be not pushed in suddenly. In all these cases, it is understood, that the quantity that can be thus introduced is in proportion to the size of the animal. I have before me at this moment the details of an experiment that I made on a horse at Alfort with M. Dupui, and in which, before the animal died, I was able, in thirty seven minutes, to inject quickly into the veins forty syringes full of air, and three syringes full into the carotid artery. (The capacity of the syringe was seventeen centilitres.) The animal died three minutes after the last injection. At the examination of the body, we found air in the azygos vein and in the thoracic duct, which contained much lymph, as well as the lymphatic vessels of the internal surface of the lungs. The heart was enormously distended with air mixed with a small quantity of blood.

[64]This is not correct, and death takes place, on the contrary, by the cessation of the motions of the heart. The right ventricle is filled with air; and this air, dilated by heat, so distends it, that it can no longer contract.

[65]The disorders which are produced in this case do not at all resemble those which follow the entrance of air into the veins. If we push towards the brain, by the carotid artery, a small quantity of air, we see almost immediately signs of a strong cerebral congestion, spasmodic stiffness of the muscles, loss of sensibility, and of the action of the senses, and all the phenomena of a real apoplexy. Respiration and the circulation go on some time without any apparent alteration, but finally these two functions become embarrassed and the animal sinks. Every thing leads to the belief, that the alteration in the circulation of the brain depends here on the presence of rarefied air in the ultimate arterial ramifications.When apoplexy is thus produced by the injection of air, if it be still forced into the artery, it breaks open violently a passage for itself, it tears the small vessels, and spreads in the parenchyma of the brain, which it makes emphysematous and crepitating under the finger. There finally returns a portion of it by the veins, which goes to the right cavities of the heart and which contributes to arrest the circulation.

When apoplexy is thus produced by the injection of air, if it be still forced into the artery, it breaks open violently a passage for itself, it tears the small vessels, and spreads in the parenchyma of the brain, which it makes emphysematous and crepitating under the finger. There finally returns a portion of it by the veins, which goes to the right cavities of the heart and which contributes to arrest the circulation.

[66]In the two examinations related by Morgagni, it appears that after a sudden death, there was found in the vessels of the brain an aeriform fluid, to the presence of which, for the want of another material cause, was attributed the death of the individual; but there is no proof that this fluid might not be developed there after death. We shall now relate a more decided case of death occasioned by the presence of air in the blood vessels; but here there is no ground for doubt, because we know the circumstances of the introduction.A locksmith, twenty three years of age, had had for five years a large tumour on the right shoulder and clavicle. His acute sufferings induced him to enter the hospital to have it removed.It was necessary in the operation to remove the middle portion of the clavicle. Thus far the success was complete; but little blood was lost, the pulse was good and the breathing easy, when the patient suddenly cried out,My blood is leaving my body! I am dead!And at the same moment he became stiff, lost his consciousness, and was covered with a cold sweat. A singular and rather loud noise was heard in the interior of his chest. The surgeon thought that he had opened the pleura by removing a portion of the clavicle, and thus given access to the air and to the blood to the right side of the thorax. The fingers of an assistant were immediately thrust into the bottom of the wound, with the view of stopping the supposed opening in the pleura, and the surgeon endeavoured to introduce into the thorax the extremity of a sound of gum elastic. When he thought that he had succeeded, he drew with his mouth the air which he supposed to be effused in the pleura. He wished then to proceed to the dressing; and, in order to do this, he substituted, for the fingers of the pupil which were at the bottom of the wound, a sponge covered with wax; but the moment the sponge took the place of the fingers, the same noise that was at first heard and which had ceased in an instant, was renewed with more force than before.The syncope and cold sweat still continued. Water thrown into his face, made him give some signs of life; but he died a quarter of an hour after the appearance of the accident I have just described, and forty five minutes after the commencement of the operation.The body was examined the next morning. They expected to find the right pleura open, much blood and air effused into its cavity and the lungs on that side collapsed. Nothing of the kind was found. The pleura was whole and there was no effusion in it. The lungs were as usual; but an opening of half an inch in extent was discovered in the external jugular vein, at the place where this vein opens into the subclavian. The cavities of the heart were large but contained no blood. Bubbles of air were observed in the vessels of the brain; the other vessels were not examined.This fact was related to me the same day, by a student who was present. It was impossible for me not to refer the death in this instance to the entrance of air into the vessels. The opening in the vein, the noise that was heard, the suddenness of the death, the absence of blood in the cavities of the heart, the presence of air in the vessels of the brain, all sufficiently indicated it. I suspected that the entrance of air had been favoured by the state of tension of the parietes of the vein, or by their morbid alteration, which did not allow them to flatten by atmospheric pressure. I thought that this phenomenon might be produced at will on animals by placing them in the same physical circumstances. I introduced then into the jugular vein of a dog, a sound of gum elastic, and I directed it towards the heart. It was hardly there before I heard the air enter the vein, and the animal fell down in syncope, with the peculiar noise which manifests the presence of air in the heart. I immediately closed the sound to prevent the entrance of more air, and the animal gradually recovered, because the quantity of air introduced had not been in sufficient quantity to produce its death. I then opened the sound, and immediately the air rushed in towards the heart, and its entrance was followed by the same consequences; but, whether from not closing the sound soon enough, or from the entrance of a greater quantity of air, the animal died unexpectedly to me. In opening it, I found all the signs of death from the sudden entrance of air. The right ventricle was distended with air mixed with a little blood.Sometimes, without any apparent alteration in the texture of the veins, its parietes do not flatten under atmospheric pressure; a simple puncture then is sufficient, as in bleeding, to admit the air into the vessels. Lieutaud relates two cases in which it appears that this took place, and several veterinary surgeons have assured me that they have heard, after bleeding in the jugular vein, a noise which indicates the entrance of air. Usually the quantity introduced is too inconsiderable to produce any evident effects. There has been communicated to me, however, a case observed by Mr. Bouley, the younger a veterinary surgeon in Paris, in which the entrance of air was followed by effects similar to those which we have related.Mery had long since observed, that, in opening the abdomen of a dog, and puncturing the vena cava above the origin of the emulgents, as the vein become emptied of blood, it filled with air, which went to the right ventricle. Haller also observed that air entered into the veins of frogs and other cold-blooded animals in consequence of a wound of some large vessel. He has shown that it was from this source that was derived that which Redi, Caldesi, and Morgagni saw circulating in the vessels of these animals, since it is not observed, when the necessary precautions are taken to prevent its introduction.Nysten has made a great number of experiments upon the injection of elastic fluids into the veins, and the results which he has obtained accord perfectly with those which we have observed. He is not satisfied with injecting atmospheric air, he has introduced in the same way a great number of other gases. He has remarked, that among the gases not deleterious he can introduce, without causing death, a much greater quantity if these gases are easily dissolved in the blood.We cannot follow him in the detail of these experiments; we shall only relate a result relative to the colouring of the blood in the lungs. He has observed, that by injecting air into the vein, so slow as not to produce the death of the animal, the colouring of the arterial blood is rendered imperfect. He is satisfied, he says, that it is not owing to the embarrassment of the lungs. The injection of oxygen does not alter this colouring. The injection of azote completely prevents it; that of the oxide of carbon does not produce any change in it. I give these results from his work; I have not had occasion to verify them myself.

A locksmith, twenty three years of age, had had for five years a large tumour on the right shoulder and clavicle. His acute sufferings induced him to enter the hospital to have it removed.

It was necessary in the operation to remove the middle portion of the clavicle. Thus far the success was complete; but little blood was lost, the pulse was good and the breathing easy, when the patient suddenly cried out,My blood is leaving my body! I am dead!And at the same moment he became stiff, lost his consciousness, and was covered with a cold sweat. A singular and rather loud noise was heard in the interior of his chest. The surgeon thought that he had opened the pleura by removing a portion of the clavicle, and thus given access to the air and to the blood to the right side of the thorax. The fingers of an assistant were immediately thrust into the bottom of the wound, with the view of stopping the supposed opening in the pleura, and the surgeon endeavoured to introduce into the thorax the extremity of a sound of gum elastic. When he thought that he had succeeded, he drew with his mouth the air which he supposed to be effused in the pleura. He wished then to proceed to the dressing; and, in order to do this, he substituted, for the fingers of the pupil which were at the bottom of the wound, a sponge covered with wax; but the moment the sponge took the place of the fingers, the same noise that was at first heard and which had ceased in an instant, was renewed with more force than before.

The syncope and cold sweat still continued. Water thrown into his face, made him give some signs of life; but he died a quarter of an hour after the appearance of the accident I have just described, and forty five minutes after the commencement of the operation.

The body was examined the next morning. They expected to find the right pleura open, much blood and air effused into its cavity and the lungs on that side collapsed. Nothing of the kind was found. The pleura was whole and there was no effusion in it. The lungs were as usual; but an opening of half an inch in extent was discovered in the external jugular vein, at the place where this vein opens into the subclavian. The cavities of the heart were large but contained no blood. Bubbles of air were observed in the vessels of the brain; the other vessels were not examined.

This fact was related to me the same day, by a student who was present. It was impossible for me not to refer the death in this instance to the entrance of air into the vessels. The opening in the vein, the noise that was heard, the suddenness of the death, the absence of blood in the cavities of the heart, the presence of air in the vessels of the brain, all sufficiently indicated it. I suspected that the entrance of air had been favoured by the state of tension of the parietes of the vein, or by their morbid alteration, which did not allow them to flatten by atmospheric pressure. I thought that this phenomenon might be produced at will on animals by placing them in the same physical circumstances. I introduced then into the jugular vein of a dog, a sound of gum elastic, and I directed it towards the heart. It was hardly there before I heard the air enter the vein, and the animal fell down in syncope, with the peculiar noise which manifests the presence of air in the heart. I immediately closed the sound to prevent the entrance of more air, and the animal gradually recovered, because the quantity of air introduced had not been in sufficient quantity to produce its death. I then opened the sound, and immediately the air rushed in towards the heart, and its entrance was followed by the same consequences; but, whether from not closing the sound soon enough, or from the entrance of a greater quantity of air, the animal died unexpectedly to me. In opening it, I found all the signs of death from the sudden entrance of air. The right ventricle was distended with air mixed with a little blood.

Sometimes, without any apparent alteration in the texture of the veins, its parietes do not flatten under atmospheric pressure; a simple puncture then is sufficient, as in bleeding, to admit the air into the vessels. Lieutaud relates two cases in which it appears that this took place, and several veterinary surgeons have assured me that they have heard, after bleeding in the jugular vein, a noise which indicates the entrance of air. Usually the quantity introduced is too inconsiderable to produce any evident effects. There has been communicated to me, however, a case observed by Mr. Bouley, the younger a veterinary surgeon in Paris, in which the entrance of air was followed by effects similar to those which we have related.

Mery had long since observed, that, in opening the abdomen of a dog, and puncturing the vena cava above the origin of the emulgents, as the vein become emptied of blood, it filled with air, which went to the right ventricle. Haller also observed that air entered into the veins of frogs and other cold-blooded animals in consequence of a wound of some large vessel. He has shown that it was from this source that was derived that which Redi, Caldesi, and Morgagni saw circulating in the vessels of these animals, since it is not observed, when the necessary precautions are taken to prevent its introduction.

Nysten has made a great number of experiments upon the injection of elastic fluids into the veins, and the results which he has obtained accord perfectly with those which we have observed. He is not satisfied with injecting atmospheric air, he has introduced in the same way a great number of other gases. He has remarked, that among the gases not deleterious he can introduce, without causing death, a much greater quantity if these gases are easily dissolved in the blood.

We cannot follow him in the detail of these experiments; we shall only relate a result relative to the colouring of the blood in the lungs. He has observed, that by injecting air into the vein, so slow as not to produce the death of the animal, the colouring of the arterial blood is rendered imperfect. He is satisfied, he says, that it is not owing to the embarrassment of the lungs. The injection of oxygen does not alter this colouring. The injection of azote completely prevents it; that of the oxide of carbon does not produce any change in it. I give these results from his work; I have not had occasion to verify them myself.

[67]When air is introduced into the vena portæ, there is not only no ill effect at the moment of injection, but there usually follows no apparent effect on the animal. It is not the same when air is injected into the veins of the general system, with so much care as not to produce instantaneous death by the dilatation of the heart. The effects do not then appear till a long time after the injection; but they are wholly different from the primary effects which we have described.These consecutive symptoms from the entrance of air into the veins are, as Nysten has remarked, the result of an obstruction of the lungs produced by the accumulation of air in the last divisions of the pulmonary artery. The embarrassment in respiration often appears at the end of half a day, it becomes greater and greater, the bronchiæ are filled with a viscid fluid; and the animal usually dies on the third or fourth day. On examination of the body, no air is found in the heart or the vessels; but the lungs, instead of being pink-coloured, are greyish, tinged with brown, and loaded with frothy blood and mucus.Boerhaave thought, that death which follows the injection of air into the veins was always owing, as it is in this case, to the presence of the air, which offers, in the small vessels, a mechanical obstacle to the passage of the venous blood.

These consecutive symptoms from the entrance of air into the veins are, as Nysten has remarked, the result of an obstruction of the lungs produced by the accumulation of air in the last divisions of the pulmonary artery. The embarrassment in respiration often appears at the end of half a day, it becomes greater and greater, the bronchiæ are filled with a viscid fluid; and the animal usually dies on the third or fourth day. On examination of the body, no air is found in the heart or the vessels; but the lungs, instead of being pink-coloured, are greyish, tinged with brown, and loaded with frothy blood and mucus.

Boerhaave thought, that death which follows the injection of air into the veins was always owing, as it is in this case, to the presence of the air, which offers, in the small vessels, a mechanical obstacle to the passage of the venous blood.

The lungs are the seat of two very different sorts of phenomena. The first, which are entirely mechanical, are relative to the rise and fall of the ribs and diaphragm, to the dilatation and contraction of the air vessels, and to the entry and exit of the air, which is the effect of these movements. The second, which are purely chemical, may be referred to the different alterations, which the air and blood experience.

These two sorts of phenomena have a mutual dependence on each other. Without the mechanical, the chemical changes could not be made; without the chemical changes, the blood would cease to become an excitant to the brain, in consequence of which that organ would no longer operate upon the diaphragm or intercostal muscles; the muscles themselves would then become inactive, and the motions of the thorax be annihilated. These phenomena, however, are put an end to in a different mannerby the death of the heart, accordingly as it happens on one or the other side.

The heart has certainly no influence over the mechanical functions of the lungs, but it contributes essentially to produce the chemical changes which are made there, by sending thither the fluid which is destined to undergo a change. When its functions then are interrupted as may happen from wounds or be occasioned by ligature, the chemical changes which should be made in the blood, are suddenly suppressed; though the air continue to enter into the lungs, from the dilatation and contraction of the chest.

Meanwhile there arrives nothing at the red-blooded heart, or[68]so little as to be insufficient for the production of the cerebral movements. The functions of the brain are consequently suspended, and of course the movements of the diaphragm and ribs.

Whenever from wound, ligature, or aneurism, the functions of the red-blooded heart or aorta cease, the functions of the lungs are terminated in the following order:

1st. There is no further impulse made upon the brain. 2dly, No further movement of that organ.[69]3dly, No further action exercised upon the muscles. 4thly, No further contraction of the intercostals or diaphragm. 5thly, The mechanical functions of the lungs cease. 6thly, Their chemical functions cease.

In the former case, the chemical changes could not be made for want of blood. Here they cannot be made for want of air. Such is the difference in the death of the lungs, in consequence of that of the heart, according as the latter is affected. But as the circulation is very rapid, there cannot be but a very short interval between the interruption of the chemical and the mechanical functions of the lungs.

FOOTNOTES:[68]After the obliteration of the ductus arteriosus, the left ventricle receives no blood but what comes from the lungs; now, if the motions of the thorax continue, it is red blood; at least so long as the air is freely admitted into the bronchial tubes, and so long as the composition of this fluid is not changed by the mixture of foreign gases.[69]These two modifications should, after what we have said, be reduced to a single one, viz. want of excitement of the brain by the arterial blood.

[68]After the obliteration of the ductus arteriosus, the left ventricle receives no blood but what comes from the lungs; now, if the motions of the thorax continue, it is red blood; at least so long as the air is freely admitted into the bronchial tubes, and so long as the composition of this fluid is not changed by the mixture of foreign gases.

[69]These two modifications should, after what we have said, be reduced to a single one, viz. want of excitement of the brain by the arterial blood.

I shall divide this chapter, as the preceding one, into two sections. In the first I shall examine, how the death of the red-blooded heart, in the second how the death of the black-blooded heart, is the cause of the death of all the parts of the body.

All the functions belong either to the animal, or to the organic life. Hence the difference of their classes. Nowthe death of those of the first class, in consequence of lesions of the red-blooded auricle and ventricle, is caused in two ways, and first, because the brain in such case is rendered inert from want of impulse, and can neither have sensations, nor exercise an influence over the locomotive and vocal organs.

Accordingly, all this order of functions is stopped, as when the encephalic mass has experienced a violent concussion. It is in this way that a wound of the heart, or the bursting of an aneurism, annihilate all our relations with external objects.

So strict a connexion between the movement of the heart, and the functions of the animal life, is not observable in those animals in which the brain, in order to act, does not require the habitual stroke of the blood. Tear away the heart of a reptile, or tie its large vessels, and it will continue for a long time to move and have sensations.

Besides, supposing even that the action of the brain were not to be suspended from lesions of the red-blooded heart, the animal life would not, on that account, be the less put an end to; because to the exercise of the functions of this life, is attached as a necessary cause, the excitement of its organs by the afflux of blood into them: now this excitement, both here and every where else, depends upon two causes.—1st, On the movement impressed, and 2dly, On the nature of the blood. At present I shall only examine the first mode of influence; the latter will come under our consideration, when we speak of the lungs.

Habitual motion is necessary to all the parts of the body alike, is a condition essential to the functions of the muscles, the glands, the vessels, and the membranes, &c. But this movement, which is partly derived from theheart, is very different from that which is communicated by the blood to the brain.

The latter organ receives an impulse by which the whole of its mass is visibly raised, an impulse, in the intermission of which the whole of its mass subsides. On the contrary, the interior movement, by which its particles are affected, is scarcely marked at all: and this depends upon the smallness and the delicacy of the vessels by which its substance is penetrated.

The contrary of this appearance is observed in the movement occasioned in the other organs by the influx of the blood into them: we see them neither rise nor subside; there is nothing like a general impulse made upon them, because, as I have said, such impulse is lost from the little resistance of the surrounding parts. On the contrary, they are penetrated by vessels of considerable magnitude, which create an intestine motion, oscillations, and impulses adapted to the actions of the tubes, lamellæ, or fibres, of which they are composed. This difference of movement may be easily conceived, by comparing the manner in which the brain on the one hand, and on the other the liver, the spleen, the muscles, or the kidneys receive their blood; indeed it is requisite that the brain should be distinguished from the other organs, in the manner of receiving its impulses, because it is enclosed in a case of bone, and consequently abstracted from the thousand other causes of agitation, to which the other parts of the body are exposed.

For we may remark, that all the other organs have about them a number of agents, which are destined to supply the place of that general impulse, which is wanting to them on the part of the heart. In the breast, the intercostals and diaphragm are continually rising and falling; the lungs and the heart are successively the seatof a dilatation and contraction. In the abdomen, there is an uninterrupted agitation produced, by the influence of respiration upon its muscular parietes; an incessantly variable state of the stomach, intestines and bladder. Lastly, from the various contractions of the muscles, the limbs have a still more evident cause of movement.

Nevertheless, it is probable that every one of the organs, as well as the brain, has a general though obscure movement impressed upon it, from the pulsation of the arteries; and hence, perhaps, we have the reason, why the greater number of the viscera, receive the impulse of the red blood upon their concave surfaces, as may be seen in the kidneys, the liver, the spleen, and the intestines. By such disposition, the impulse of the heart is less divided.[70]

From what has now been said, we may add another reason to that which we have before given, for establishing in what way the functions of the animal life are interrupted from cessation of action in the red-blooded heart. We may now also begin to explain the same phenomenon in the organic life. The reason of such interruption in both the lives is the same. It is as follows:

1st. In the case of death affecting the red-blooded heart; the intestine movement, which proceeds from the manner in which the arteries are distributed within thesubstance of all the organs, both of the one and the other life, is suspended; hence there exists no farther cause of excitement for the organs: they must consequently die.—2dly. The causes of the more extensive and general movements of the organs are abstracted; for almost all these causes depend upon the brain. We respire and move, only while the brain is alive: but as the brain must be in a state of collapsus, as soon as it ceases to receive the impulse of its blood, its influence must be evidently annihilated.

Hence it follows, that the heart exercises over the different organs two modes of influence; the one direct and immediate, the other indirect, and made through the medium of the brain, so that the death of the organs in consequence of the death of the heart, is immediate or mediate.

We have sometimes examples of partial death, analogous to this sort of general death. Thus, when the circulation is impeded in a limb, and the red blood no longer distributed to its parts, such parts become at first insensible and paralytic, then gangrenous. The operation of aneurism furnishes us with too many instances of this phenomenon, which by ligature, may be produced also in the living animal. Undoubtedly the principal cause of death in these cases, is the want of that stimulus which it is the business of the particles of the red blood to create, in contradistinction to those of the black blood, but the absence of the intestine movement in question, is by no means a less real cause of such death.

As for the interruption of the nutritive process, it cannot be admitted as a cause of the symptoms which succeed after the obliteration of a large artery. The slow, the gradual, and insensible way, in which this function is performed, does not accord with the suddenand instantaneous production of those symptoms, especially as they affect the animal life; for this is annihilated in the limb at the very instant when the blood ceases to flow into it, just in the same way as it is, when by the section of its nerves, the influence of the brain is abstracted.[71]

Besides the preceding causes, which, when the heart is dead, suspend in general the whole of the animal and organic functions; there is another cause of death which especially affects the greater number of the latter, such as the processes of nutrition, exhalation, secretion, and therefore digestion, which is only performed by means of the secreted fluid. This cause of death to which I refer, consists in the necessary stop which is put to these different functions, in consequence of their no longer receiving the materials upon which they are exercised. Nevertheless, such term arrives by degrees only, because they receive the materials on which they act, from the capillary, and not from the general circulation. Now the capillary circulation, is only subject to the influence of the insensible contractile powers of the parts in which it is performed; and is exercised independently of the heart, as may be seen in the greater number of reptiles, where the heart may be taken away, and the blood be notwithstandingobserved to oscillate for a long time afterwards in the minuter vessels.[72]It is manifest, then, that whatever quantity of blood is left in the capillary system at the period of the death of the heart, will for some time afterwards be sufficient to keep up the functions in question, and that such functions in consequence will only gradually cease.

The following is a general view of the manner in which the annihilation of all the functions succeeds to the interruption of those of the heart.

The animal life is terminated—1st, Because the organs of which it is composed, are no longer excited without, by the movement of the neighbouring parts, nor within, by the blood.—2dly, Because the brain, from want of excitement, can no longer be a cause of excitement.

The organic life is terminated—1st, Because, as in the animal life, there is a want of external and internal excitement for its different viscera.—2dly, Because there is a want of the materials on which its functions are particularly exercised.

There are a number of other considerations, however, besides those which we have mentioned, which prove the reality of the excitement of the organs, from the movement communicated to them by the blood, as well as the reality of the cause, which we have asserted to be that of their death, when such excitement ceases.

For, 1st.—The organs which are penetrated only by the serum of the blood, such as the hair, the nails, the tendons, and cartilages, enjoy a less degree of vitality,and a less energetic action, than those in which the blood is made to circulate, either immediately by the heart, or by the insensible contractile powers of the parts themselves.

2dly.—When the white organs are inflamed, they receive an augmentation of life, a superabundance of sensibility, which frequently put them on a level in many respects with those organs, which in their natural state are endowed with the highest degrees of life and sensibility.

3dly.—Those organs which habitually receive the influx of the red blood, when inflamed, exhibit, in every instance, a local exaltation of the phenomena of life. In the two preceding instances, it is true, indeed, that the change of vital powers, precedes in point of time, the change which is made in the circulation; the organic sensibility of the part, has been augmented before the blood is carried thither in greater quantity; but afterwards it is the afflux of such increased quantity of blood, which keeps up the unnatural action which has been established. A determined quantity of blood in the ordinary state of the part, is necessary to the maintenance of that state; but when the part receives a double or triple increase of energy, its excitant also must be doubled or tripled; for in the exercise of the vital powers, there are always three things to be remarked; the power inherent in the organ; the excitant which is foreign to it; and the excitement which is the product of the two.

4thly.—It is doubtless, for this reason, that the organs to which the blood is habitually carried by the arteries, enjoy a degree of life, proportionate to the quantity of fluid by which they are injected. Such phenomenon may be observed in the glans penis, in the corpora cavernosa, in the nipple, in the skin of the face, and theactions of the brain, whenever the blood is directed with impetuosity towards them.

5thly.—The whole of the circulatory system, is thrown into greater action from the exaltation of the whole of the vital phenomena, just in the same way as the particular circulation of any part is augmented, when the particular phenomena of the life of that part are increased. The use of spirituous liquors, and spices to a certain quantity, is followed for a time by a general increase of energy in the powers of the system. The access of inflammatory fever will double and triple the intensity of life.

In these considerations I have only regarded the movement which is communicated to the organs by the blood. In another place I shall call the attention of the reader to that species of excitement, which is produced by the nature of the blood, by the contact of its component particles when in a state of oxydation or otherwise, with the different parts of the body. The reflections which I have offered, will be amply sufficient to convince us how much the blood, independently of the materials which it conveys with it, by its simple influx, is necessary to the activity of the organs, and consequently how much the cessation of the functions of the heart, must influence the death of the organs.

FOOTNOTES:[70]It should not be lost sight of, that all this discussion turns upon the application of a principle which is by no means proved: viz. that the different organs, in order to exercise their functions, require to be agitated by a partial or general motion. We have already made it appear, that as it respects the brain, this jarring of the whole mass, to which Bichat attributes so much importance, appears to be a circumstance purely accidental from the entrance of the arterial blood. The same may be said of the oscillatory motion produced in the other organs by the pulsation of the ultimate arterial ramifications.[71]When the passage of the arterial blood to a muscle is stopped, a more or less complete numbness soon takes place; and this effect is too sudden to be attributed to the want of nutrition; and as certainly it is not owing to the want of agitation by the pulsations of the small arteries; for if, the artery is left free, and a ligature is applied upon the vein, the pulsations are increased rather than diminished and yet the numbness appears as quick as before.When the muscle has been a long time without receiving blood, gangrene seizes upon it; and this can then be attributed, in great measure, to the want of nutrition. The diminution of the temperature, which necessarily takes place in an organ in which the blood is not renewed, must also contribute to this disorganization.[72]We know that the blood pushed into the arteries distends the parietes of these vessels, and brings into action their elasticity; now, after the heart has ceased to act, these parietes, by contracting, can impart, for some instants, an oscillatory motion to the fluid contained in their cavity.

[70]It should not be lost sight of, that all this discussion turns upon the application of a principle which is by no means proved: viz. that the different organs, in order to exercise their functions, require to be agitated by a partial or general motion. We have already made it appear, that as it respects the brain, this jarring of the whole mass, to which Bichat attributes so much importance, appears to be a circumstance purely accidental from the entrance of the arterial blood. The same may be said of the oscillatory motion produced in the other organs by the pulsation of the ultimate arterial ramifications.

[71]When the passage of the arterial blood to a muscle is stopped, a more or less complete numbness soon takes place; and this effect is too sudden to be attributed to the want of nutrition; and as certainly it is not owing to the want of agitation by the pulsations of the small arteries; for if, the artery is left free, and a ligature is applied upon the vein, the pulsations are increased rather than diminished and yet the numbness appears as quick as before.When the muscle has been a long time without receiving blood, gangrene seizes upon it; and this can then be attributed, in great measure, to the want of nutrition. The diminution of the temperature, which necessarily takes place in an organ in which the blood is not renewed, must also contribute to this disorganization.

When the muscle has been a long time without receiving blood, gangrene seizes upon it; and this can then be attributed, in great measure, to the want of nutrition. The diminution of the temperature, which necessarily takes place in an organ in which the blood is not renewed, must also contribute to this disorganization.

[72]We know that the blood pushed into the arteries distends the parietes of these vessels, and brings into action their elasticity; now, after the heart has ceased to act, these parietes, by contracting, can impart, for some instants, an oscillatory motion to the fluid contained in their cavity.

Whenever the heart ceases to act, general death is produced in the following manner:—1st. For want ofexcitement the cerebral actions are annihilated, and consequently an end is immediately put to all sensation, locomotion, and utterance. Besides, for want of excitement on the part of the blood, the organs of these functions would cease to act, even supposing that the brain were to remain unaffected, and exert upon them its accustomed influence. Thus the whole of the animal life is suddenly suspended, and at the instant of the death of the heart, the individual is dead to what surrounds him.

The interruption of the organic life, which has commenced by the death of the heart, is produced at the same time by that of the lungs. The brain being dead, the mechanical functions of the lungs must cease: the chemical functions of the lungs must cease also, for want of the materials on which they are exerted: the latter are directly interrupted, the former through the medium of the brain.

After this the progress of death is gradual. The secretions, the exhalations, the nutritive actions are put an end to. The latter are first arrested in those organs which receive the more immediate impulse of the blood, because in these, such impulse is necessary to the performance of the functions. The paler organs are less dependent on the influence of the heart, and consequently must be less affected by the cessation of its action.[73]

In the successive termination of the latter phenomena of the internal life, the vital powers continue to subsist for some time after the loss of the functions: thus, the organic sensibility, and the sensible and insensible contractilitiessurvive the phenomena of digestion, secretion, and nutrition.[74]

The vital powers continue to subsist in the internal life, even when the corresponding powers of the animal life, have suddenly become extinct: the reason is plain: the power of perceiving and moving organically does not suppose the existence of a common centre; for the animal perceptions and motions, the action of the brain is requisite.

The phenomena of death are concatenated in the above order in all aneurismal ruptures, in all wounds of the heart or larger vessels, in all cases of polypi formed in the cardiac cavities,[75]of ligature artificially applied, of compression exercised on the parietes of the heart by humours, abscesses, &c. &c.

It is in this manner also that we die from sudden affections of the mind. The news of a very joyful, or a very melancholy event, the sight of a fearful object, of a detested enemy, of a successful rival, are all of them causes capable of producing death. Now in all these instances, it is the heart, which is the first to die, the heart, whose death successively produces that of all the other organs, the heart, on which the passion is exerted.

And hence we are led to some considerations on syncope, an affection exemplifying in a less degree the same phenomena, which in a greater one, is offered us in cases of sudden death.

The causes of syncope are referred by Cullen to two general heads: Of these there is one set which according to him affect the brain, another set which affect the heart. Among the first, he places the more violent impulses on the mind, and various evacuations, but it is easy to prove, that the brain is only secondarily affected in syncope produced by passion, and that it is the heart, whose functions in all these cases are the first to be interrupted. The following considerations, if I am not mistaken, will leave but little doubt on this head.

1st.—I have proved, in speaking of the passions, that they never affect the brain in the first place; that the action of this organ, in consequence of their development, is only secondary, and that every thing relating to our moral affections has its seat exclusively in the organic life.

2dly.—The phenomena of syncope when produced by lively emotion, are similar in every respect to those of syncope, the effect of polypi or dropsy of the pericardium, but in the latter, the affection of the heart is the primary one, and should in consequence be the same in the former sort of syncope.

3dly.—At the moment when syncope takes place, we feel the attack at the heart, and not in the brain.

4thly.—In consequence of lively passions, which may have occasioned syncope, we find that the heart and not the brain becomes diseased, nothing is more common than organic affections of the former from sorrow, &c. The different sorts of madness, which are produced by the same cause, for the most part have their principal seat insome of the viscera of the epigastrium, and in such case, the irregularity of the cerebral action is the sympathetic effect of the profound affection of the internal organ.[76]

5thly.—I shall prove hereafter, that the cerebral system does not exert any direct influence over that of the circulation; that there is no reciprocity between the two, and that the changes of the first are not followed by similar changes in the second, however much the changes of the second may modify the first. Destroy all nervous communication between the brain and the heart, and the circulation will go on as usual; but if the vascular communications be intercepted, the cerebral action vanishes at once.

6thly.—Palpitations and other irregular movements of the heart are often the effect of the same causes, whichin some individuals are the occasion of syncope. In such cases, it is easy to discover the seat of the affection, and such smaller effects of the passions on the heart, are very well calculated to throw light upon the nature of the greater.[77]

From these many considerations, we may conclude that the primitive seat of the attack in syncope, is the heart, which does not cease to act, because the action of the brain has been interrupted, but because it is the nature of some of the passions in such way to affect it, the brain at the same time, suffering a temporary death, because it no longer receives the fluid, which is necessary to its excitement. The nature of syncope is well enough illustrated, by the vulgar expression of being sick at heart.

It is of no importance to our present purpose, whether syncope depend on polypi, on aneurism, or be the result of some violent emotion. The successive affection of the organs is always the same. They die for the moment in the same way, as they really perish when the heart is wounded, or a ligature put upon the aorta. In the same manner also are those sorts of syncope produced, which succeed after any great evacuation of blood, pus or water.The heart is affected from sympathy, the brain for want of its excitant.[78]

Those cases of syncope which are occasioned by peculiar odours, by antipathies, &c. appear also to be attended with the same progression of symptoms, though their character be much less easily understood. There is a great difference between syncope, asphyxia, and apoplexy, in the first it is by the heart, in the second by the lungs, in the third by the brain that begins the general death of the body.

Death, as it happens in consequence of disease, in general exemplifies a concatenation of these different symptoms. The circulation, respiration, or cerebral action cease, the other functions are afterwards interrupted of necessity, but in these sorts of death, it rarely happens that the heart is the first to die. This however is sometimes the case. After long continued suffering, great suppuration, and sometimes, in dropsy, certain fevers, and gangrenes, one fit of syncope comes on after another,at last a longer one succeeds, and the patient dies, but whatever be the part affected, whatever the diseased viscus or organ, whenever the phenomena of death commence by the heart, they succeed each other as we have described them to do in sudden death, from lesion of that organ. In other cases, the heart is the last to act, is the ultimum moriens.

In general, in morbid affections, we much more commonly observe the ingress of death to be made by the lungs, than either by the heart, or the brain.

Whenever disease is terminated by syncope, the lungs are found to be almost empty, and if not affected by any organic disease, are collapsed, occupy a part only of the cavity of the thorax, and are of their natural colour.

The reason of this anatomical fact is simple. The circulation which has been suddenly interrupted, has not had time to fill the vessels of the lungs, as happens when death begins, by affecting the lungs or the brain. The truth of this fact I can vouch for, having frequently ascertained it by dissection, and in general, as often as death commences by the heart, or the larger vessels, such vacuity of the lungs may be considered as universal.

I have remarked it in the bodies of persons who have died from great hemorrhage from wounds or aneurismal rupture and violent passion, as well as in those who have suffered by the guillotine. The same phenomenon may be seen, by inspecting the lungs of any animal, which is killed in our butcheries.

In killing the animal slowly by the lungs, that organ might be filled with blood. Its taste would then be different from that which it naturally possesses, and resemble that of the spleen. Our cooks know well how to take advantage of that state of infiltration in which the latter viscus is generally found.

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