I might add a number of examples to these, which I have already related of the blackening of the organs by the venous blood. Thus, the kidney of a dog exposed, while the animal is dying of asphyxia, is much more livid than in its natural state, the spleen also and the liver, when divided, emit only black blood, instead of that mixture of red and black blood which is observable, in the section of these organs, upon an animal which breathes freely.
But I trust that we have facts enough to establish it as a certainty, 1st, That the black blood after the interruption of the chemical functions of the lungs, continues for some time to circulate, and 2dly, That it penetrates into the organs, where it replaces the red blood; these circumstances explain the reason, why on opening the body we always meet with black blood even in the vessels which are destined for the circulation of arterial blood.
In the last moments of existence of whatever death the individual may have died, we shall always observe the lungs become embarrassed and cease to perform their office, for some time previous to the total suspension of the functions of the heart. The blood makes its circle through the system, after ceasing to receive the influence of the air, and consequently in its venous state; accordingly it must remain so in the organ in every case, althoughthe circulation be much less evident, than in asphyxia, for it is in this circumstance that consists, the great peculiarity of asphyxia. The following phenomena may now be easily understood.
1st. When the left auricle and ventricle together with the large divisions of the aorta, on opening the body, are found to contain blood, such blood is always black. The fact is familiar to those who are in the habit of dissecting. In exercising my pupils on the surgical operations, I have always observed that when the open arteries are not entirely empty, their contents are composed of venous blood.
2dly, The corpus cavernosum is always gorged with this sort of fluid, whether flaccid or in a state of erection. For I have seen it in the latter state in two subjects brought to my amphitheatre. One of these men had hanged himself, the other had died of concussion of the brain.
3dly, The blood which is found in the spleen is never red; but sometimes on the exterior, and sometimes on the concave surface of this organ, I have observed spots of a scarlet colour, for which I cannot account.
4thly, After death, the mucous membranes lose the red colour by which they are characterized during life. They assume a black and livid hue.
5thly, Blood extravasated in the brain of persons in a state of apoplexy, is almost always found to be black.
6thly, Sometimes, instead of accumulating inwardly the blood injects the surface of the body. In such case the face, the neck, and shoulders swell, and are infiltrated with blood. I have frequently remarked this sort of phenomenon in the subject, but have never found it coincide with any internal extravasion.—The colour of the skin is then of a purple or deep brown, an evident signof the sort of blood with which it is injected, and is evidently produced by the stagnation of the black blood in the external capillary system, not by the reflux of the blood from the veins.
I shall not dwell any longer upon the numerous consequences of the above established principle. I shall only observe, that when death commences by the circulatory system, the preceding phenomena are not to be remarked, or at least very little perceptible.
Let us now pass on to the influence of the black blood upon the organs of which it penetrates the tissue.
To determine what the influence of the black blood is upon the organs, I shall first remark, that the property of the red blood is to stimulate them, and keep up their vital actions. This will be proved by the following observations:
1st, Compare phlegmon, erysipelas, and inflammatory tumours (to the formation of which the red blood is essentially requisite) with scorbutic spots, and petechiæ, produced by the black blood. The first will be found connected with the exaltation of the vital powers, the second with their depression.
2dly, Examine two men, the one with a rosy coloured skin and large breast, announcing vigour of lungs, the other with a pale and sallow countenance, and narrow chest: in these the vigour of the chemical combinations which are made in the lungs, should certainly be very different.
3dly, The greater number of gangrenes in old men, begin with a lividity in the part, a lividity which is evidently the index of the absence or diminution of the arterial blood in the part.
4thly, The redness of the branchiæ of fish is always the sign by which their vigour may be recognised.
5thly, The redder the granulations of wounds, the more healthy is their nature; the paler or browner they are, the less has the part a tendency to cicatrise.
6thly, The lively colour of the face, and the ardent eye, coincide with the energy of the cerebral actions in certain fevers.
7thly, The more developed the pulmonary system of animals, the more active are the chemical processes of the lungs, and the more developed and perfect the general life of their different organs.
8thly, Youth, which is the age of vigour, is that also when the red blood predominates in the system. The arteries of old people are smaller, the veins larger than those of the young. It is a fact universally known, that at the two extremities of life the proportions of the two vascular systems are inverted.
I am ignorant of the manner in which the red blood excites and keeps up the life of the parts. Perhaps the principles by which it is coloured become combined with the different organs to which it is distributed. In fact there is a considerable difference between the phenomena of the general and those of the capillary system.
In the first, the blood in changing its colour, leaves behind it the principles which made it red; in the second, the elements to which its blackness is owing, are rejected by respiration and exhalation. Now, this union of the colouring principles of the arterial blood, may probably constitute a material part of the excitement which isnecessary to the action of the organs.—If such be the case, the black blood as it does not contain the materials of such union, cannot act as an exciting cause. This idea, however, I offer only as a probability, and am by no means prepared to defend it as a truth; it may be ranked on a par with that of the sedative action, which I have said may be excited by the black blood on the different parts—for, however probable an opinion may appear, there should be no real importance attached to it as an opinion only.
Without regard then to any system, let us inquire how the black blood, from its contact with the various parts, is the occasion of their death; how it acts on the parts of the animal life, and how it acts on those of the organic life.
All the organs of the animal life depend upon the brain; now, we have seen that the black blood paralyses the cerebral powers almost suddenly. In the state then of asphyxia, the locomotive, the vocal and sensitive organs, must be inactive. From the same cause, their exercise must be suspended in all those different experiments where black blood is injected into the brain, the other parts receiving the red blood as usual. But when the black blood circulates throughout all the system, when the whole of the organs, as well as the brain, are submitted to its influence, then there are two other causes of death connected with those which have been mentioned.
1st, The nerves, which are penetrated by it, for that very reason are no longer capable of keeping up the communication between the brain and the senses on the one hand, and on the other, between this same viscus and the locomotive or vocal organs.
2dly, The contact of the black blood with these organs themselves annihilates their actions. Inject the cruralartery of an animal with the black blood taken from one of its veins, and the movements of that member will be shortly afterwards enfeebled, or wholly paralyzed. In this experiment, the upper part of the artery, for manifest reasons, should be that to which the pipe of the syringe should be fixed.
I am aware that as to this experiment, it may be asserted that the ligature of the artery, of itself, is capable of paralyzing the limb. In fact, such circumstance has happened twice with me, but I have also had occasion to observe, that it does not necessarily follow the ligature of this vessel, as it does the ligature of the aorta: when the latter vessel is tied, all movements cease at once; notwithstanding all which, the result of the injection of black blood, is almost constantly that which I have asserted it to be;—I say almost, 1st, Because I have once seen it fail in its effect, though done with the requisite precautions; 2dly, Because the debility, which is induced, both in duration and degree, will be according to the strength of the animal on which the experiment is made.
There is also occasioned in this experiment, a manifest suspension of the sensibility of the animal; it is not indeed so ready to appear as the loss of motion; but it always comes on, especially if the injection of the black blood be repeated three or four times, with small intervals.
A similar, but a more tardy effect may be produced by adapting to the canula, which has been placed in the crural artery of an animal, a tube which has been previously fixed to the carotid of another animal, and then by asphyxiating the latter.[96]The organs of the internallife are not dependent on the brain, and therefore are not affected by the suspension of the cerebral action in asphyxia. It is the influx of the black blood which is the immediate cause of their death.
I have already demonstrated what the influence is of this blood upon the organs of the circulation. We have seen how the heart ceases to act, as soon as it is penetrated by it; it is owing in part to the injection of the arterial and venous parietes themselves, by the vasa vasorum, that the vessels are forced to suspend their actions.
It will be always a difficult thing to prove, that the secretions, the exhalations, and the process of nutrition, could not be made from venous blood, because the circulation of this sort of blood in the arteries, does not continue for a sufficient time, to allow of observations, or the manner in which these functions would be affected by it. On this subject, however, I have made some essays. 1st, I exposed the inner surface of the bladder of a living animal, after having previously divided the symphysis pubis, and opened the lower belly, I then examined the oozing of the urine from the orifices of the ureters, while I asphyxiated the animal. 2dly, I divided the vas deferens, with the view of observing, whether the semen would flow or not, during such state.
In general, I have had occasion to remark, that during the circulation of the black blood in the arteries, no fluids appear to issue from the different secreting tubes. But I confess, that in all these experiments, and in other similar ones which I have made, the animal is too much agitated, and the limits of the experiments too circumscribed, for any thing like a well founded judgment to be formed on the subject in question. It is chiefly from analogy, then, that I am led to conclude, that the black blood is unfit for the purposes of exhalation and nutrition: suchsupposition also accords well with divers of the phenomena of asphyxia.—1st, The want of exhalation from the skin during the state of asphyxia, is probably the reason of the phenomena of the animal heat in such sort of death.[97]2dly, In asphyxiating animals very slowly during digestion, I have uniformly observed, that the bile ducts, and duodenum, contain a much less quantity of bile, than they do at such time, when these parts are exposed in the living animal.—3dly, As the blood loses nothing from the exercise of these functions, it must of course accumulate in the vessels; and in fact, it is very fatiguing and unsatisfactory, to dissect the bodies of those who have been hanged or asphyxiated with the vapours of charcoal, from the fluidity and abundance of their blood. But this abundance, perhaps, may depend upon the weakness of the absorbents. In other sorts of death, the absorbents continue for some time to act upon the serous portion of the blood remaining in the vessels. In asphyxia there is neither secretion nor absorption.
The excretions also appear to be affected much in the same way. The bladder of asphyxiated persons has been observed by Portal, to be very much distended. Such distension, no doubt is occasioned by the urine already secreted before the accident which was the cause of their deaths. In general, the asphyxiæ which are occasioned by the circulation of the black blood unmixed with any deleterious substance, are not accompanied with those spasms, which in so many other sorts of death, are sofrequent. These spasms, which evacuate the organs of their fluids, should be carefully distinguished from the simple relaxations of the sphincters, by which analogous effects are produced.[98]In asphyxia, all is debility, in asphyxia, we never see that augmentation of life, that development of power, which so frequently mark the latter movements of the dying.
Hence also perhaps, the great flexibility of the members of asphyxiated persons. The stiffness of the muscles appears to depend in many cases, on the circumstance of death having come on precisely at the moment of their contractions. The fibres remain approximated, and coherent among themselves;[99]in asphyxia, on the contrary, as there exists an universal relaxation and want of action in the parts, they remain so after death, and yield to whatever impulse may be communicated to them.
I confess, however, that this explanation is subject to a difficulty which I cannot solve. Persons asphyxiated by mephetic vapours, perish nearly in the same way as those who are drowned; if the cause of their death be different, its effects are the same, as may be seen by opening the carotid of two dogs at the same time, that into the lungs of the one are injected the vapours of charcoal, and into those of the other, a certain quantity of water, which water, as in the drowned, is soon reduced into a state of foam.
Notwithstanding this similitude of the last phenomena of life in the two cases, the members in the first remain for a certain time warm and supple, while those in the second, especially if the body be plunged into water during the experiment, become very suddenly stiff and frozen. Let us return, however, to our subject. We may conclude from the various facts and considerations related in this chapter, 1st, That when the chemical functions of the lungs are suspended, the functions of all the other organs are suspended also, from the presence of black blood within their substance. 2dly, That the death of the organs in general, coincides with that of the brain, and the heart, but is not immediately derived from them. 3dly, That if it were possible for the brain and heart to receive an influx of arterial blood, while the others were dying, from that of the venous blood, they would doubtless continue to exert their accustomed actions. 4thly, That, in a word, asphyxia is a general phenomenon, developed at the same time in all the organs, but especially in one of them.
From this manner of regarding the influence of the black blood upon the different parts of the body, it appears that death is very soon the result of its circulation in the arteries. Nevertheless, certain organic defects have sometimes prolonged after birth, the mixture of the two sorts of blood, a mixture which is known to be made in the fœtus. Such was the malconformation mentioned by Sandeford, in a child, the aorta of which arose by a branch from each of the ventricles. Such also appears, at first sight, to be the opening of the foramen ovale in the adult.
We shall remark, however, that the existence of this foramen, does not suppose the passage of the black blood into the red-blooded auricle, as is generally believed.For the two semi-lunar valves, between which it is situated when met with after birth, are necessarily applied to each other by the pressure which the blood contained in the auricles, exercises upon them, when these cavities are simultaneously contracted. The foramen must be at such time shut, and its obliteration much more exact, than that of the opening of the ventricles, by the mitral and tricuspid valves, or that of the aorta and the pulmonary artery, by the sigmoid valves. With all this, the foramen ovale is actually very often found open in the subject, and when not so, nothing is easier than to destroy the species of adhesion which is contracted by the two valves which close it. This may be done with the handle of a scalpel, without any solution of continuity, the parts appear to be unglued.
The oval hole when in this way artificially made, presents the same disposition, with that which is sometimes exemplified in the carcase. Now if this disposition be examined, it will be seen that when the auricles contract, the blood must make an obstacle to itself, and that it cannot pass from one into the other of these cavities. It is an easy thing to be convinced of the mechanism of which I speak, by means of two injections of a different colour, made at the same time from both sides of the heart, from the vena cava, and the pulmonary veins.
From what we have said of the influence, which is exercised by the movement and the different principles of the blood, it is evident that the death of the white organs must be different from that of the red ones. Asphyxia can hardly reach them, but of the manner in which they die I confess that I know but little.
FOOTNOTES:[94]It is not possible to remove by this means a great portion of air contained in the lungs, for the last ramifications of the air-tubes being flexible, their parietes soon come in contact, and thus oppose the exit of the air contained in the bronchial cells.[95]These observations have been made on the great mammalia, and there has not been remarked any difference of colour.[96]The difference that is remarked in the results of this experiment, compared with that in which the venous blood is introduced by means of a syringe, arises probably from this, that in the first the blood that is forced into the artery has already begun to coagulate.[97]The deficiency of cutaneous exhalation in the last moments of life may contribute a little perhaps to the preservation of animal heat; but we have shown that there are other more powerful causes for this phenomenon. This deficiency of exhalation united to the inaction of the secretory organs, in the very short period in which the black blood runs in the arteries is an altogether insufficient cause to explain the abundance of blood that is found in the vessels of those who have died of asphyxia.[98]This is not an uniform fact, and it is even very common to find, in persons who have been hung, the bladder completely empty.[99]The moment respiration ceases, and the source of heat is consequently cut off, it is not astonishing that an animal body should become cold quicker in water then in a much less dense fluid, like the air. It should also be remarked that the water, on account of the evaporation that takes place on its surface, has almost always a temperature below that of the surrounding air.
[94]It is not possible to remove by this means a great portion of air contained in the lungs, for the last ramifications of the air-tubes being flexible, their parietes soon come in contact, and thus oppose the exit of the air contained in the bronchial cells.
[94]It is not possible to remove by this means a great portion of air contained in the lungs, for the last ramifications of the air-tubes being flexible, their parietes soon come in contact, and thus oppose the exit of the air contained in the bronchial cells.
[95]These observations have been made on the great mammalia, and there has not been remarked any difference of colour.
[95]These observations have been made on the great mammalia, and there has not been remarked any difference of colour.
[96]The difference that is remarked in the results of this experiment, compared with that in which the venous blood is introduced by means of a syringe, arises probably from this, that in the first the blood that is forced into the artery has already begun to coagulate.
[96]The difference that is remarked in the results of this experiment, compared with that in which the venous blood is introduced by means of a syringe, arises probably from this, that in the first the blood that is forced into the artery has already begun to coagulate.
[97]The deficiency of cutaneous exhalation in the last moments of life may contribute a little perhaps to the preservation of animal heat; but we have shown that there are other more powerful causes for this phenomenon. This deficiency of exhalation united to the inaction of the secretory organs, in the very short period in which the black blood runs in the arteries is an altogether insufficient cause to explain the abundance of blood that is found in the vessels of those who have died of asphyxia.
[97]The deficiency of cutaneous exhalation in the last moments of life may contribute a little perhaps to the preservation of animal heat; but we have shown that there are other more powerful causes for this phenomenon. This deficiency of exhalation united to the inaction of the secretory organs, in the very short period in which the black blood runs in the arteries is an altogether insufficient cause to explain the abundance of blood that is found in the vessels of those who have died of asphyxia.
[98]This is not an uniform fact, and it is even very common to find, in persons who have been hung, the bladder completely empty.
[98]This is not an uniform fact, and it is even very common to find, in persons who have been hung, the bladder completely empty.
[99]The moment respiration ceases, and the source of heat is consequently cut off, it is not astonishing that an animal body should become cold quicker in water then in a much less dense fluid, like the air. It should also be remarked that the water, on account of the evaporation that takes place on its surface, has almost always a temperature below that of the surrounding air.
[99]The moment respiration ceases, and the source of heat is consequently cut off, it is not astonishing that an animal body should become cold quicker in water then in a much less dense fluid, like the air. It should also be remarked that the water, on account of the evaporation that takes place on its surface, has almost always a temperature below that of the surrounding air.
In recapitulating what has been said in the preceding chapters, with respect to the influence of the lungs over the heart, the brain, and all the organs, it is an easy matter to form an idea of the successive termination of the whole of the functions, when the phenomena of respiration are suspended either mechanically or chemically.
The following is the manner in which death supervenes, when the mechanical phenomena of the lungs are interrupted, either from the causes mentioned in the 5th chapter, or from similar ones, such as the rupture of the diaphragm, which I have twice had occasion to observe,[100]or from a fracture of a great number of the ribs, or the sternum.
1st. The mechanical functions of the lungs cease. 2dly. The chemical functions of the lungs cease also. 3dly. The cerebral actions are put an end to. 4thly. The animal life is interrupted. 5thly. The general circulation is interrupted. 6thly. The capillary circulation is interrupted.
The phenomena of death, are differently concatenated, when they begin by the suspension of the chemical functions of the lungs: which may happen, 1st, From breathing in a vacuum; 2dly, From the obliteration of the passage of the trachea, by foreign substances introduced into it, or by tumour from without, or strangulation, accumulation of fluid in the air cells, &c.; 3dly, From different inflammatory affections, schirrhi, &c. of the cavities of the mouth or throat. 5thly, From want of respirable air, as on the summit of high mountains. 6thly, Fromthe introduction into the air cells of non-respirable gases, &c. &c. In all these cases, the following is the order of the phenomena of death.
1st. The chemical functions of the lungs are suspended. 2dly. The functions of the brain are interrupted. 3dly. Sensation, locomotion, the voice, the mechanical phenomena of respiration cease. 4thly. The action of the heart, together with the general circulation is annihilated. 5thly. The capillary circulation is put an end to, together with the processes of secretion, exhalation, absorption, and digestion. 6thly. The animal heat of the system dies away.
The influence of the black blood as I have said, is always the great agent in this double sort of death, but it is not the only one: if that were the case, the phenomena of all the asphyxiæ would be alike. It is true that in every sort of asphyxia, the black blood ceases to become red blood, and circulates in the arteries, such as it is in the veins; but notwithstanding the uniformity of this phenomenon, there can be nothing more varied, than the symptoms and progress of these accidents. In some of them, death is long in taking place; in others, almost instantaneous: the phenomena developed in the last moments of existence, are alike in none of them. The state of the organs, and that of the powers which they preserve after death, are as various.
1st, Asphyxia varies with respect to its duration; in sulphurated hydrogenous gas, in nitrous gas, and certain vapours arising from privies and sewers, it is quick in taking place. In carbonic acid gas, azote, in pure hydrogen, water, and a vacuum, its progress is slower.
2dly, Asphyxia varies with respect to its attendant phenomena. At times, the animal is violently agitated and suddenly convulsed; at others, it appears to lose its powers gradually; to pass into a state of sleep, and from sleep into a state of death. In comparing the numerous effects arising from the vapours of sewers, from those of charcoal, from the different gases, from drowning, and other causes of asphyxia, we find them almost as various, as the causes themselves.
3dly, The phenomena which make their appearance after death, are as variable. Compare the cold and frozen carcase of a drowned man, with the remains of one who has been suffocated. Read the result of the different experiments of the Institute, upon the affections of the galvanic fluid in the different asphyxiæ; examine Halle’s detail of the symptoms which accompany the mephitism of sewers; approximate the numerous observations, which are scattered about in the works of Portal, Louis, Haller, Troja, Pechlin, Bartholin, and Morgagni; repeat the most common experiments on the submersion, strangulation, and suffocation of animals; and you will observe the greatest difference in all these sorts of asphyxia, they are each of them characterized, by a peculiar state of the bodies of the animals, which have been submitted to the experiment.
To inquire into the causes of such differences, we must first divide the asphyxiæ into two classes. 1st, Into those which happen from the simple want of respirable air, and 2dly, Into those, where to this first cause is joined also that of the introduction of some deleterious substance into the lungs.
In the first class, the immediate cause of death, appears to be the simple presence of the black blood, in the various parts of the body, the general effect of which is alwaysthe same, in whatever manner produced; accordingly, the attendant symptoms and secondary results of all these sorts of death, are nearly alike, their duration the same, and if it varies, it varies only in consequence of the more or less complete interruption of the passage of air into the lungs.
This variety in the duration and intensity of the asphyxiating cause, may nevertheless occasion some variety in the symptoms also; such as a greater or less lividity and swelling of the face, a more or less considerable embarrassment of the lungs; but all these differences indicate only so many modifications of the cause, 1st, A man who is hanged, does not die as a man who is suffocated by an inflammatory tumour, or a pea or bean which perchance may have fallen into the trachea.[102]2dly, An animal will perish much more slowly under a vessel of air, than when the trachea is tied. 3dly, The symptoms of asphyxia, when occasioned by a great rarefaction of air, or by a suffocating heat, are much less slowly produced, than where the cavity of the lungs is opened.
In all these cases the cause of death, namely the absence of red blood in the arterial system, is simple and unique, but according to the greater or less oxygenation of the venous blood, will be the appearances after death, for the longer the process of asphyxia endures, the less irritability will there be found in the system.
But if the cause of asphyxia, have been the introduction of some deleterious fluid into the lungs, then thevariety of the symptoms will depend upon the difference in the nature of the fluid. In these cases the cause is of two kinds: 1st, There is no red blood in the system. 2dly, A pernicious fluid is present in the system. All the gases however do not act as deleterious substances: in pure hydrogen for instance, the animal perishes only as it would from the want of respirable air.
But when a man in descending into a common sewer, into a cellar, or into any place where putrid matters are accumulated, falls into asphyxia at the moment when he inspires their exhalations, and when such state is attended with convulsive movements and extreme agitation, then indeed, there must be something more in the cause of his death, than a simple suspension of the chemical functions of the lungs.
In fact, together with the mephitic vapour, there continues to enter into the lungs a sufficient quantity of air to keep up life and its different functions. 2dly, Supposing even that the quantity of mephitic air were such as to leave no place for the entrance of respirable air, still the death ensuing should only be gradual, without agitation and convulsion, were it occasioned only by the absence of such air: now the very different way in which it supervenes, very evidently indicates the action of a deleterious substance, upon the animal œconomy.[103]
These two causes then act together, in those asphyxiæ which are produced by certain gases, sometimes the one predominates, sometimes the other. If the deleterious substance be violent, it kills before the action of the black blood can have produced much effect, if weak, it is the black blood, which is principally the cause of death.
The asphyxiæ then, which are produced by the gases, differ only, in consequence of the nature of the deleterious substance, which variesad infinitum. In some of the aeriform fluids indeed it is supposed to be known, but in the greater number of them it is not so:[104]I shall notice therefore in a general way the effects, which result from the action of the deleterious substance, remarking at thesame time, that the symptoms by which they are displayed, are strongly or weakly marked, according to the age and temperament of the individual.
Deleterious substances introduced into the lungs, together with the mephitic vapours of which they form a part, can act only in two ways. 1st, By affecting the nerves of the lungs, which re-act on the brain. 2dly, By passing into the blood, and exercising their influence, by means of the circulation on the various organs of the system.
I can easily believe that the simple action of such a substance on the nerves of the lungs, may have a very marked effect on the economy, and be capable of troubling the functions of the system very sensibly; much indeed in the same way as with some individuals a mere odour, or the sight of a hideous object, will occasion syncope, in the same way that an irritating enema will suddenly awake the system into life, or the introduction of certain substances within the stomach, will be felt throughout the body, before such substances can have passed into the circulatory torrent. We meet at every moment with examples of these very remarkable phenomena, produced by the simple impressions of foreign bodies on the mucous surfaces; I cannot deny that deleterious substances may act in the same way upon the nerves of the lungs, though we must not exaggerate the sphere of this mode of action.[105]
In fact, I am not acquainted with any one example, where the contact of a deleterious substance with a mucous membrane, has been the sudden cause of death. It may indeed be productive of such effect after a certain time, but never at the moment of its action; nevertheless, in those asphyxiæ which are produced by mephiticvapour, so rapidly does death come on, that the black blood can scarcely have had the time to exert its influence upon the body. The principal cause of the cessation of the functions is manifestly the action of the pernicious substance.
These considerations, then, incline me to believe, that these substances pass into the blood through the lungs, and that in circulating with the blood they carry to the organs the immediate cause of their death. Such passage into the blood has already been suspected by many physicians; the truth of the fact appears to be indubitably proved by the following reflections.
1st, It can hardly be doubted, that the poison of the viper and many other venomous animals, and that the saliva of rabid animals, pass into the system of the blood, and are taken up either by the veins or the lymphatics.
2dly, It appears to be very certain, that a portion of the atmospheric air is actually absorbed through the mucous membrane of the lungs itself, and not by means of the absorbent system. Now, if this be the case, I know not what should hinder the passage of mephitic vapour in the same way.[106]We are not sufficiently acquainted with the limits of the particular sensibility of the membrane of the air cells, to say that it cannot give a passage to such vapour.
3dly, The respiration of an air which has been charged with the exhalations arising from oil of turpentine, communicatea particular smell to the urine. It is thus that this fluid is affected from the residence of the persons in a newly varnished room. In this case it is evidently by the lungs in part, that the odoriferous fluid has its passage into the blood, and so on to the kidneys. In fact, I have often assured myself by breathing out of a bottle through a tube, air so charged (in which case it could not act on the cutaneous surface) that the smell of the urine undergoes a change. If, then, the lungs will admit a variety of substances, which do not enter into the composition of respirable air, for what reason should they not admit the mephitic vapour of mines and subterraneous places.
4thly, The respiration of humid air produces dropsy. The extent of the fact has been exaggerated, indeed, but the fact itself is true. It proves, that an aqueous fluid may pass into the blood, and consequently that other substances may pass into it also.
5thly, If an animal be asphyxiated in sulphurated hydrogenous gas, and a plate of metal some time after its death be placed under one of its muscles, the surface of the plate contiguous to the muscle, will be sensibly sulphurated. The foreign principle, then, which is here united with the hydrogen, must have been introduced into the circulatory torrent by the lungs, and have penetrated with the blood into all the parts. The deputies of the Institute have observed this phenomenon in their experiments. I have made a similar remark in asphyxiating animals with nitrous gas. A phenomenon of the same nature accompanies the exhibition of mercury.
From the above, we have nearly a right to conclude, that the different deleterious substances of which the gases are the vehicles, do actually pass into the blood, and so affect the organs. Of this matter, however, I shall adduce some further proofs.
I have ascertained by a number of experiments, that atmospheric air, or any other aeriform fluid, may be made to pass into the blood without alteration.
Divide the trachea of a dog, inject the air-cells strongly with common air, and continue to retain it in the lungs. The animal will immediately discover signs of great distress and agitation; if an artery now be opened, the blood will be emitted in a frothy state.
If hydrogen have been employed, it may easily be ascertained that the nature of the fluid is unchanged, by placing a candle over the bubbles which are disengaged.
When the blood for the space of thirty seconds has flowed in this state, the animal life of the creature will be finished, and death ensue, with all the symptoms which accompany the insufflation of air into the black-blooded system of vessels. The re-admission of air into the lungs, will have no effect in restoring the animal to life, for as soon as frothy blood can flow from any one of the arteries, it must already have affected the brain with its pernicious influence.
In this case it may be perceived, that the causes of death are the same as those which proceed from the insufflation of air into a vein. In the one instance the air passes at once from the lungs into the arterial system. In the other, from the veins across the lungs and then into the arteries.
When we open the bodies of animals, which have been killed in these experiments, the whole apparatus of the red-blooded vascular system, is found to be filled with air bubbles of various sizes. In some circumstances, the blood will be transmitted in the same state into the general capillary system, and from thence into the veins; in others it will be stopped in the capillary system, and in such cases, though the circulation may have continuedfor some time after the suspension of the animal life, not a single particle of air will be discovered in the veins.
In these experiments which I have frequently repeated, I have never found that the least fissure has been made in the bronchiæ; nevertheless, I confess that it is difficult to say, whether this be so in their last ramifications. The following phenomenon, however, may throw some light upon the subject; for as often as air is pushed into the lungs with great violence, there will be produced an emphysema of the breast, or neck, from the infiltration of this fluid among the cellular texture, in addition to its passage into the blood. But if the impulse be moderate, and the quantity of air injected not much beyond the measure of a full inspiration, it will pass into the blood only, and not into the cellular texture.[107]
The experiments of which I have given the detail, exemplify phenomena which do not indeed take place in theordinary process of inspiration, and therefore I allow that no very rigorous induction can be drawn from them, with respect to the passage of deleterious substances into the mass of the blood; nevertheless it appears to me, that they very much confirm the probability of such fact, which besides is demonstrated by many of the preceding remarks. I shall conclude, then, that such passage is real. In fact, we have seen 1st, That the sole transmission of the black blood into the arteries, will not account for the infinitely various phenomena exemplified in the different sorts of asphyxiæ; 2dly, That the simple contact of the deleterious substance with the nerves of the lungs, can by no means be the cause of a death so rapid as that which is occasioned by these accidents; 3dly, That, therefore, we are forced as it were to suspect the passage of the poison itself into the blood; 4thly, That a number of considerations are in favour of such suspicion, and thus that the fact is proved both directly and indirectly.[109]
This principle being once established, a variety of results must flow from it. Of the first of these, of the mode of action, namely, which the deleterious substancemust exercise upon the different organs, I shall say nothing, having nothing to offer but conjecture.
I shall accordingly content myself with inquiring what system it is which is particularly influenced by these substances, when mingled with the blood.—Now, 1st, This system appears to be the nervous one, and that portion of it especially, which presides over the parts of the animal life, the organic functions being only secondarily affected; 2dly, Of all the nervous system, the brain is that part which is the most affected; 3dly, Under this relation Monsieur Pinel appears to me to have been right, in placing some of the asphyxiæ (those for instance which are occasioned by the presence of a deleterious substance) among the neuroses. On this head the following considerations should leave us little doubt.
1st, In all the asphyxiæ, when the presence of a deleterious substance cannot be doubted, the symptoms consist of two general and opposite sets of phenomena, of spasm and torpor. Of two workmen who had come up out of the sewer of the street St. André des Ares, the one sat himself down upon a bulk, and fell into a state of asphyxia; the other with irregular convulsive movements, proceeded as far as the rue Battoir, and then fell down asphyxiated. The Sieur Verville, in consequence of inhaling the breath of a man who was lying in a state of asphyxia from the vapour of lead, fell down suddenly, and in a short time became convulsed. The vapour of charcoal intoxicates, as it is said. I have seen animals asphyxiated with other gases, and perishing with a stiffness, such as could be produced only by the most violent spasm. The centre of all these symptoms, and the organ from which they emanate, undoubtedly is the brain, and they depend upon its irritation or compression.
2dly, The animal life is always interrupted before the organic life, wherever the asphyxiating cause has been of a compound nature. Now the centre of the animal life is the brain.
3dly, I have proved when the animal perishes from the circulation of the black blood in the arteries, that the brain is especially affected even then; but in the same way, that is, by the cephalic arteries, the deleterious substance itself, may be introduced into the brain.
4thly, I have pushed a variety of deleterious gases (for example, sulphurated hydrogen) into the brain, and also some of those substances which vitiate the nature of these gases. The animal has always perished with symptoms of spasm, or torpor, and in general the death which is occasioned by the different gases, is always similar to that which is produced by the introduction of pernicious substances into the brain.
5thly, The consequences of these asphyxiæ, when life has been restored, invariably suppose a lesion of the cerebral system, such consequences consist of palsy, tremour, wandering pains, and derangements of the exterior apparatus of the senses.
From all these multiform experiments and considerations, we may surely conclude, that it is on the brain and nervous system that the deleterious principle, introduced into the blood, must act; from the death of these parts, that of the others is derived.
In this case the different organs no doubt are directly enfeebled, and may perhaps be immediately affected by those principles, which flow into them together with the blood, but all such phenomena, are even more visible in the animal, than in the organic life.
Let us not forget however, that a part at least of the cause of this sort of death, consists in the influence of thevenous blood upon the organs, and that this influence must ever be in proportion to the length of time that such blood continues to circulate. The differences then which are found in the asphyxiæ, may be said to proceed from the greater or less effect of the venous blood upon the system, from the different nature of the various deleterious substances inspired, and from the age and temperament of the individual affected.
I have just spoken of sudden death. I shall now enlarge a little on that which is the slow effect of disease. Physicians must be well persuaded, that by far the greater number of diseases, put an end to life by an affection of the lungs. Whatever be the seat of the principal affection, be it either an organic lesion, or a general disorder of the system, the action of the lungs in the latter moments of existence, becomes embarrassed, the respiration difficult, and the oxydation of the blood, but slowly effected; accordingly this fluid must pass into the arteries, almost in the venous state.
The organs therefore which are already enfeebled, must be much more readily affected by the pernicious influence of such blood, than those which are subject to it, in the different cases of asphyxia. In this way the loss of sensation, and intellect, are very shortly the effect of embarrassment in the lungs; and ensue as soon as the brain begins to be penetrated with the fluid which is so transmitted to it.
By degrees the heart and all the organs of the internal life, cease also to move. It is here the black blood which arrests these vital motions, which have alreadybeen enfeebled by the disease. Such weakness, the consequences of the disease, is very rarely the immediate cause of death, it only prepares it, by rendering the organs more susceptible of the alteration in the healthy state of the blood. Such alteration is almost always the immediate cause of death. The disease then, is only an indirect cause of death in general, it kills the lungs, and the death of the lungs occasions that of all the other parts.
From hence it may be easily conceived, why the small quantity of blood contained in the arterial system of the subject, is almost always black. For 1st, The greater number of deaths begin by the lungs. 2dly, We shall see that those which have their commencement in the brain, are equally the cause of this phenomenon. Accordingly there can be only those, in which the heart ceases suddenly to act, after which the red blood can be found in the aortic ventricle, and auricle. Such appearance is seldom found, excepting in the bodies of persons who have perished from extensive hemorrhagy.
From the frequency of deaths beginning with an embarrassment of the lungs, may be conceived also the reason, why this organ is so frequently gorged with blood in the carcase in general, the longer the agony, the heavier and fuller are the lungs. When such fulness is found, together with black blood in the red-blooded system, whatever the disease may have been, it may be pronounced that death has begun in the lungs. In fact the concatenation of the phenomena of death is from one of the three organs, from the lungs, brain, or heart, to all the others. Now when death begins in the heart, the pulmonary vessels are generally empty, and there is red blood in the aortic system. On the other hand, if death has begun in the brain, there is then indeed a certain quantityof blood in the arteries, but the lungs are empty, unless, when gorged with blood, by some antecedent affection.