MOTOR NERVES. — From the experi ments of Vulpian, Reichert, and H. C. Wood, it may be considered proved that in the warm-, as well as in the cold blooded animals strychnine depresses di rectly the motor nerves, although it is probable, as is insisted upon by Poulsson, that the spinal cord is also paralyzed, because in certain frogs, and also in mammals, the paralysis appears to be complete at a time when the motor nerves are still capable of responding to stimuli (H. C. Wood).
CHIcuLATiox.—Strychnine has a very decided effect upon the circulation. Richter, Mayer, Schlesinger, and Klapp have noted a decided rise of arterial pressure before or about the time of the first convulsion, not due, however, to the convulsion, as it occurs in curarized ani mals in which artificial respiration is maintained. Mayer and Richter affirm that the rise of arterial pressure is due to stimulation of the vasomotor centres. Klapp and Reichert have shown that primary stimulation of the vasomotor centres by strychnine is followed by a fall of arterial pressure and vasomotor paralysis; also that very large closes produce an immediate depression of the vasomotor centres and a fall of arterial pressure. An increase in the pulse-beat and in the pulse-rate follows after the injection of moderate doses of strych nine, probably due to a stimulation of the heart-muscles and its ganglia. When injected intravenously in large closes, Reichert noted, at first, a transient in crease of pulse-rate, clue to the immedi ate, overwhelming action of the undis tributed strychnine upon the inhibitory apparatus of the heart; second, a lessen ing of the pulse-rate, due to slight stim ulation of the pneumogastric endings; third, a marked increase in the pulse rate, due to pneumogastric depression; and, finally, a decrease in the pulse-rate, due to an influence upon the heart muscle or its ganglia.
Strychnine is among the most constant and powerful of the respiratory stimu lants. In a series of very careful experi ments H. C. Wood found that the injec tion of strychnine produced in the dog an extraordinary increase in the respira tory air-movement, which was never less than 75 per cent., and sometimes rose to 300 per cent. A. Obermeier has found, experimentally, that small doses of strychnine produce in the rabbit no distinct alteration in the elimination of carbonic acid, but that after large closes there is a rise of the animal temperature and a very noticeable increase in the elimination of carbonic acid. It has been suggested that the increase in tem perature which occurs after poisonous doses may be produced by the severe muscular action during the convulsions; small doses of strychnine have no ap parent effect upon the body-temperature.