Physiological Researches on Life and Death

by Xavier Bichat

For the purpose of satisfying myself that this motion took place in the spinal marrow and not in the dura-mater, I cut this membrane in the whole extent of the opening made in the vertebral canal, and I was able easily to convince myself that the motion was from the swelling of the spinal marrow. I am not however certain that there is not a slight rising of the organ from the dilatation of the large veins in the anterior part of the vertebral canal, but this dilatation cannot be considerable, on account of the fibrous layer which covers the posterior face of these veins.

[92] Active substances introduced into the veins can act on the organs in many ways at once. They have at first their peculiar action which is nearly uniform, whatever may be the mode of administration; but they produce also other effects resulting from their physical properties, and these last may vary according to the form in which they are introduced.

The substances introduced into the circulation have necessarily to pass through a double system of capillary vessels, and must consequently be very greatly subdivided. Hence we see that a viscid fluid would be unable to enter the smallest vessels, and that by remaining in those which can admit it, it will prevent the passage of the blood, and occasion a congestion either of the lungs or some other organ, according as it has been injected into a vein or an artery. A substance like quicksilver, which without being viscid, exhibits great cohesion among its particles, will produce precisely the same effects. The globules will never divide below a certain size. The air itself, mixed in a fluid such as the blood, will form bubbles which will divide with more difficulty as they become smaller, and which can finally stop in the entrance of the capillaries, so as to prevent a free passage of blood in a part of these vessels. Boerhaave thought that it was always thus, by opposing a mechanical obstacle to the capillary circulation of the lungs, that air injected into the veins produced the death of the animal.

In an experiment in which I proposed to myself to change the nature of the blood by a foreign fluid, I injected into the jugular vein of a dog, an ounce of Olive oil, thinking that this substance would circulate without inconvenience with the blood; but it was not so, and the animal died in a few minutes after the injection.

In examining the organs after death, I saw that the oil had closed the last ramifications of the pulmonary artery, and that it had also stopped the circulation and respiration, by preventing the passage of the blood to the left side of the heart, by the pulmonary veins. An injection made with a thick solution of gum tragacanth produced precisely the same phenomena as the oil.

An inert, impalpable powder, suspended in water, immediately produces death, if injected into the jugular vein, because it shuts up the last divisions of the pulmonary artery.

If the injected substances are not divided at first in the blood, so as to spread uniformly into the different branches, death does not take place so quickly, because a part of the sanguineous canals remains free for the circulation. This is the case when we inject quicksilver or air in so small a quantity as not to produce instantaneous death. The congestion, in this last case, is often alone sufficient to produce it after a certain time; in the other case, there is added to the obstruction a real pneumonia caused by the presence of quicksilver in the obliterated vessels. We shall now relate four experiments of M. Gaspard, which will show the effects of the stagnation of this fluid in different organs.

“First Experiment. I introduced into the jugular vein of a small dog, four days old, thirty six grains of quicksilver purified through goat’s skin. Soon after he refused to suck, lost his vivacity, motility and heat, had dyspnoea and fever, and died at the end of twenty four hours, having been all the time much colder to the touch than the other pups with whom he was. On opening the thorax, the lungs were found much inflamed, almost hepatized, heavy, puckered up and full of mercury.”

“Second Experiment. I injected into the left carotid artery of a sheep, very near the brain, half an ounce of mercury with water; I then tied with a double ligature the open vessel. The animal immediately manifested pain, and was for an instant immoveable, the head inclined, with stupor and a prominence of the eyes, which were extraordinarily open; then bending on the fore legs, twisting of the head and neck on the right shoulder, with a kind of stiffness or convulsive elasticity, which was always present till death, and returned, as by the effect of a spring, when I straightened the neck. Two hours after, standing impossible, state of drowsiness, some convulsive motions of the limbs, the left eye swelled, red and inflamed. The next day, the same state, almost total annihilation of the animal or external life, copious excretion of mucus by the left nostril, the eye still very large and inflamed. The third day, the same state; death took place fifty hours after the injection. On examination of the body it was found that the left eye was in a state of suppuration and contained mercury; the thyroid, pharyngeal auricular, lingual, labial, nasal and cerebral arteries of the left side, were admirably injected with this metal which run out under the instrument; but their capillary terminations contained none of it, and we could see to what ramification, to what sized caliber it had penetrated, and the point where it was unable to pass; the left nasal cavities exhibited a very pretty reticulated appearance, brilliant and silvery. Moreover all the organs of this side were red, inflamed and swelled by the presence of the foreign body, and it was curious to see the half of the thyroid gland, the tongue, the cheeks and the lips thus red and inflamed to the median line, whilst the other half was sound and pale; the left brain was slightly inflamed and especially the plexus choroides. Besides, I was unable to discover a globule of quicksilver in any of the other organs.”

“Third Experiment. I forced with a pewter syringe into the crural artery of a large dog, a drachm and a half of quicksilver mixed with common water. The animal, immediately after the double ligature, did not manifest any sign of pain, and walked, bearing less on that limb, which was very sensibly cold, though not paralyzed. But about an hour after, he refused food, manifested by piercing cries acute pain, constant agitation, frequent change of place, and a very evident state of suffering; the limb soon after grew warm, became hot to the touch, with an obscure pulse under the tendo Achillis. This state of fever and pain continued the whole day and night. The next day, the limb was swollen and exhibited a phlegmonous œdema preserving the impression of the finger; the plaintive cries were continual. On the third day his condition was still worse, and I then killed him from compassion sixty hours after the injection. I had carefully noticed the matter of the excretions, without discovering a particle of quicksilver in them. On examination of the body, I could not discover it in any organ, except the limb subjected to the experiment, which was swollen, inflamed and oedematous in all its textures; we observed abscesses in it of different sizes, containing quicksilver, pus, sanies and much gas, coming from the incipient gangrene of the parts; the metal usually occupied the centre of all the abscesses; the mercurial globules flowed out when I cut the skin, the cellular texture, the muscles and especially the small arteries, which were admirably injected by it; gelatinous exudations occupied the interstices of the muscles.”