1913.] arising from Rivalry of Antagonistic Reflexes. 247 



left muscle in a period of concurrence of the stimuli covering more than 

 3 sees. With r ' ® , and all stronger combinations tried, there was obtained 



1. Xa 



no rhythmic stepping movement at all, although excellent steady contractions 

 and inhibitions. 



Weaker stimuli tend, in my experience, to give slower rhythm. Other 

 factors in the production of the rhythm, for instance, the ratio between the 



.o" 



A 



Fig. 6. — Reflex rhythm (imperfect stepping) evoked in the isolated extensor of knees, 

 right and left, by concurrent stimulation of the antagonistic afferents, right and left 

 peroneals, r.p. and l.p. Decerebrate cat. In Observation A the stimulus values are 



too weak r -P- jjj cm - . i n Observation B they are too strong r.p. 11 cm. bc-th 

 l.p. 18 cm. J l.p. 12-5 cm. 



observations are from the same experiment as fig. 4, where good and regular reflex 



stepping is obtained with stimulus values r -P- 15 cm - . i n Observation A it is note- 

 vv 8 l.p. 17 cm. 



worthy that the stimulation of l.p. is so weak that it of itself produces no obvious 



contraction of the contralateral muscle and only the merest trace of relaxation of 



the ipsilateral muscle. Yet its presence is documented at once when the concurrent 



stimulus is added in the response being then not steady but rhythmic. Further 



explanation in text, p. 246. 



strengths of the antagonistic stimuli, change, however, of necessity also in 

 such comparisons. Still my facts, as far as they at present go, clearly 

 indicate the above tendency. Thus figs. 4 and 6 are from the same 



y X 6 



experiment. In fig. 6a the stimuli were j— jg> an d the beats are 9 during 



8'5 sees., while in fig. 4, observation 3, where the stimuli were y— the 

 beats are 7 during 5 - 2 sees. Again fig. 7, observations A, B, and C are all 



