Page:Treatise on poisons in relation to medical jurisprudence, physiology, and the practice of physic (IA treatiseonpoison00chriuoft).pdf/29

 body. But by much the larger proportion seem on the contrary to act on one or more organs only, not on the general system.

Of the poisons which act remotely through a sympathy of distant parts with an organic injury of the textures directly acted on, many appear to act sympathetically on the heart alone. Taking the mineral acids as the purest examples of poisons that act independently of absorption into the blood-vessels, it will be seen on inquiry that all the symptoms they produce, in addition to the direct effects of the local injury, are those of depressed action of the heart,—great feebleness, fainting, imperceptible pulse, cold extremities. Even the less prominent of the secondary symptoms are almost all referrible to a depressed state of the circulation. In particular, they are not necessarily, and indeed are seldom actually, blended with any material symptom of disorder in the brain; which certainly could not be the case if the general or whole system suffered.

With respect to that more numerous class, which act remotely either through the medium of the blood or by the transmission along the nerves of an undiscernible impression made on their sentient extremities, some certainly possess a very extended influence over the great organs of the body; but the greater number are much more limited in their sphere of action. Some act chiefly by enfeebling or paralyzing the heart, others principally by obstructing the pulmonary capillaries, others by obstructing the capillaries of the general system, others by stimulating or depressing the functions of the brain or of the spinal cord, others by irritating the alimentary canal, others by stimulating one or another of the glandular organs, such as the salivary glands, the liver, the kidneys, or the lymphatic glands.

Some poisons of this kind act chiefly, if not solely, on the heart. The best examples are infusion of tobacco, and upas antiar. Sir B. Brodie observed, that when the infusion of tobacco was injected into any part of the body, it speedily caused great faintness and sinking of the pulse; and on examining the body instantly after death, he found the heart distended and paralyzed, not excitable even by galvanism, and its aortal cavities filled not with black, but with florid blood, while the voluntary muscles were as irritable as after other kinds of death. The upas antiar he found to be similarly circumstanced. Arsenic and oxalic acid are also of this kind. In an animal killed by arsenic, and in which the gullet and voluntary muscles continued long contractile, Dr. Campbell found the heart immediately after death containing arterial blood in its aortal cavities, and insensible to galvanism. Dr. Coindet and I frequently witnessed the same facts in animals killed with oxalic acid: When the heart at the moment of death was completely palsied and deprived of irritability, we saw the intestines moving, and the voluntary muscles contracting long and vigorously from the mere contact of the air.