332 Dr. K. Sassa. Observations on Rejiex 



at the same rate as those evoked in and transmitted to it by the afferent 

 nerve. The above results in frogs are therefore in agreement with those 

 latest observations referred to above, and are confirmed by investigations 

 made with the string galvanometer (1, 6, 10). 



30 per sec. 



A 







</yuuyyyyuinn/yvinnjyuu\jytjuuuuyuuin/ 



20 per sec. 



B 













Fig. 2. — Semitendinosus reflex-preparation of spinal frog. The mechanical vibration of 

 muscle synchronous with stimulation frequency. A = tibial nerve ; B = peroneal 

 nerve ; Number = distance between coils. 



When the rate of excitation is low, e.g., 20-30 per second, I have 

 frequently failed to show the synchronism of reflex response with that of 

 the exciting stimuli, though this is clearly evident in the direct tetanus 

 produced by stimulating the motor nerve to the muscle. This is often the 

 case when the excitation at low frequency gives a comparatively high reflex 

 contraction, and in some preparations where the reflex reaction is irregular. 

 The synchronism between the frequency of stimulation of a skin spot of 

 the hind limb and the rhythm, of the resulting reflex reaction is soon 

 abolished owing to the irregularity of the reflex response. 



(3) The Course of Be/lex Contraction Produced at various Stimulatiori- 

 Frequencies. — The course of reflex tetanus is both irregular and variable, 

 at whatever frequency and intensity of excitation it is evoked, as compared 

 with that of direct muscular tetanus. Nevertheless, in typical records 

 some relation between the course of reflex tetanus and the rate of stimu- 

 lation-frequency which produces it, is usually observed. 



With low frequency of stimulation (below 30 per second) it is noted 

 that the reflex contraction, after rapidly attaining its maximum, tends to 

 persist. Often one or two minutes' excitation does not reduce the average 

 height of reaction, though irregular undulations may be seen in the course 



