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local action of the poison on the nerves,—a mode of operation which weare constrained likewise to admit in the case of some other narcotics.(See p. 13 : also Muller’s Physiology, by Baly, vol i. p. 630). Some ofthe local effects produced by hydrocyanic acid are those of an irritant:such are, the acrid impression made by the vapour on the nose andmouth—the ptyalism—the vomiting and purging—and the redness of themucous membrane of the stomach.
(b.) Absorption. —That hydrocyanic acid becomes absorbed, is provedby its having been detected by Krimer (quoted by Dr. Christison, p. 15),in the blood of animals poisoned with it, and by the odour of it exhaledby various parts of the body.
(c.) Are the remote effects of this acid caused by its absorption? —Inmany cases the operation of hydrocyanic acid on the system is so rapid,and death so speedily follows the application of the poison, that we can-not satisfactorily account for the effects by the slow process of absorp-tion : and lienee many persons have felt themselves constrained to admitthe agency of the nerves. I have before (p. 27) alluded to this subject,and have quoted a passage from Muller’s Physiology, in which the opera-tion by absorption is defended. Further information on this point willbe found at p. 627, vol. i. of this celebrated work. The principal argu-ments which have been adduced in favour of the agency of absorption arethe following: first, that the acid produces no remote effects whenapplied either to the nerves or brain: secondly, that applied to the tongueor stomach, it operates as an energetic poison, although the nerves ofthese parts were previously divided : thirdly, that if the acid be appliedto a part where circulation is arrested, the operation of the poison isprevented : fourthly, the activity of the acid is in proportion to theabsorbing powers of the part with which it is placed in contact.(Seep. 18).
(d.) Organs affected. —The parts specifically affected by this acid arethe brain and true spinal system. The pain in the head, the insensibi-lity, and the coma, are evidence of the cerebral affection; while thetetanic convulsions depend on the disorder of the true spinal system.Marx ( die Lehre von d. Giften, l er . Bd. 2 e . Abt. S. 154,) mentions thefollowing experiment performed by Wedemeyer ( Versuche uber das Ner-vensystem, S. 241, Vers. 7), and which shews the independent action ofthe acid on the spinal marrow: the spinal cord of a dog was dividedbetween the last dorsal and first lumbar vertibne, so that the hind legswere completely paralyzed and insensible to mechanical irritants: hydro-cyanic acid was then introduced into one of the hind legs;—in oneminute symptoms of poisoning commenced, the hind as well as the forelegs were violently convulsed,—and in twelve minutes the animal wasdead. The affection of the respiratory and circulatory systems producedby hydrocyanic acid is probably only secondary : that is, is the result ofthe influence of this agent over those parts of the nervous system fromwhich the respiratory organs and heart derive their nervous power.The insensibility caused by hydrocyanic acid occurs too rapidly, in manycases, to be the result of asphyxia caused by paralysis of the muscles ofrespiration.
(e.) Condition of the brain and spinal marrow. —The precise pathologi-cal condition of the brain and spinal cord of an animal under theinfluence of hydrocyanic acid, cannot be positively determined, and is,