The author had studied the action of eserine, eseroline and urethane on some reflex activity of the central nervous system of rabbit and the result is as follows:
1) Injections of eserine in doses of 1mg per kg body weight markedly lengthened the cremasteric reflex time and 0.1-0.25mg per kg body weight shortened the cremasteric reflex time, but at the beginning of the injection the reflex time was temporarily lengthened.
2) Injection of eseroline in doses of 0.2-0.5mg per kg body weight had no effect on the cremasteric reflex time and the pharyngeal reflex time, and 1-8mg shortened these reflex times.
3) Injections of urethane in doses of 5-50mg lengthened the reflex time. Among these results the initial depression of these reflex activities of eserine may be attributed to the presence of urethane grouping in the molecule of eserine.