Physiological Researches on Life and Death

by Xavier Bichat

Nevertheless, there are many differences between death from asphyxia, and death from lesion of the brain. 1st, The animal life in the latter sort of death, is generally interrupted at the very instant of the shock or blow. In the former it is terminated only in proportion as the black blood penetrates the substance of the brain.—2dly, In the greater number of the asphyxiæ, the circulation does not immediately cease, the blood is only gradually blackened, and continues for some time to be moved onwards by the agitation of such parts as are still under the influence of the brain. On the contrary, in lesion of the brain, the interruption of respiration is sudden; the blood also loses its red colour at once: on the other hand, the animal life being suddenly arrested, the organs of volition become immovable on the spot, and are capable no longer of favouring the motion of the blood. This remark is particularly applicable to the breast, the parietes of which facilitate very much the pulmonary circulation, and even the movements of the heart by their rise and fall, for in such alternation of motion consists the true influence which the circulation receives from the respiratory process.

But after all, these two sorts of death may be more or less similar to each other according to the way in which they happen. The differences which I have pointed out are by no means general. Thus, when asphyxia is sudden, as when for instance the air of the lungs is pumped out with a syringe, there are neither livid spots, or fulness of the lungs to be met with. The circulation ceases quickly, and the phenomena of death are such as are observable when the brain is suddenly destroyed.

On the contrary, if the death of the brain be slow, and the process of respiration for a certain time continued, the capillary system of the lungs will be gorged with blood, and the general capillary system be filled also. The circulation in such case will be slow to cease, and the phenomena of death like those of many of the asphyxiæ. Thus the promptitude or slowness of death, proceeding from lesion of the brain, will occasion all the differences.

It has been often a question in what way criminals die, who are hanged. In some, the vertebral column is luxated, and in others, want of respiration is the cause of death.[122] But whenever there is luxation, there is at the same time asphyxia, and in such case asphyxia is produced, both because the pressure of the cord intercepts the passage of the air, and because the intercostals and diaphragm are paralyzed.

From what I have now said, a comparison may be made between the three kinds of death upon which I have expatiated. This comparison, according to my ideas, is of importance: I shall give some features of it. Generally speaking, there is a greater similarity in the two modes by which the death of the brain, or that of the lungs produces the death of the organs, than between either of these modes, and that, where the death of the heart is followed by the same effect.

But 1st, There is always black blood in the red-blooded system, when death begins either by the brain or the lungs. When the functions of the heart are suddenly suspended, the arterial system contains a portion of red blood only.

2dly, In the two first cases, the circulation continues for awhile; in the third, it is immediately suppressed.

3dly, When the death of the organs is a consequence of the death of the heart, they die, because they cease to receive that excitement, to which they are accustomed from the motion of the blood. When their death is produced by that of the brain or lungs, they die not only because they lose the excitement above-mentioned, but because they are penetrated by a fluid which is incapable of keeping up their actions, &c. The reader will easily finish the parallel which I have thus begun.

In red and cold-blooded animals, the death of the organs succeeds much more slowly to that of the brain, than in red and warm-blooded animals. We cannot assign the reason of this fact, because we do not know the difference of the arterial blood from the venous blood of these animals, nor the effect which is produced on their organs by the contact of either sort of blood with them.