Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.

parts receive no impulse at all from that centre, whether mental or physical; and although those parts may still be perfectly healthy in themselves, yet are they thus incapable of taking part in voluntary acts. (See p. 242 and Notes on p. 477.) " Furthermore, whatever interferes materially with the conduct- ing power of nerve-fibre, or the generating power of nerve ves- cicle, (gray matter,) will constitute a paralyzing lesion. In the first place, poisoning of the nervous matter will operate in this way : For instance, soak a portion of the nerve of a living ani- mal in chloroform, or ether, or opium, and that nerve will fail to propagate the normal nervous force as long as the influence of the poison lasts. In a similar way, the poison of lead in the human system may paralyze, either by weakening the conduct- ing or the generating power of the nervous matter. Poisons formed in the living system may operate in the same way; such as retained urinary or biliary principles, or the poisons of rheu- matism, gout, &c. " Secondly, any morbid process which greatly impairs the natu- ral structure of nerve matter will paralyze. Thus inflamma- tion will do this ; so also will atrophy, or wasting from want of sufficient supplies of nutrient matter, as where the flow of blood is lessened, or cut off. The opposite conditions of harden- ing, and so of red or white softening, of the nervous matter be- come paralyzing lesions from the same reason, viz., that they greatly impair or destroy the nerve structure. " Thirdly, a solution of continuity of nerve fibre will paralyze. Cut a nerve across, and you have immediate palsy of the parts which the nerve supplies below the section. This solution of continuity from a final melting down of the fibres is, I have no doubt, the more frequent cause of sudden paralysis in cases of softening, or in cases of sanguineous effusion. " Fourthly, pressure on a nerve or nervous centre will paralyze. Of this we have many proofs as regards nerves. A nerve, as for instance, included by a ligature, or compressed by a tumor, is paralyzed thereby. A fracture of the skull, with depressed bone, will paralyze, if the brain is sufficiently compressed. An apo- plectic clot on the exterior of the brain paralyzes by compression; 41