1913.] arising from Rivalry of Antagonistic Reflexes. 245 



The threshold stimulus for r. nerve had been found slightly higher than 

 that for left in this preparation ; the two stimuli although not equal (as shown 

 later v. infra) were certainly not far from equal. Then, for obtaining 

 observation, fig. 5, the r. nerve stimulus was increased to 13 cm. and 1. nerve 

 stimulus to 16 cm. Both stimuli were therefore increased, but that of r. 

 nerve much more than that of 1. nerve, the steepness of ascending intensity 

 of the physical stimulus being much greater between 15 cm. and 13 cm. 

 than between 17 cm and 16 cm. of the scale. This unequal increase of 



Fto. 5. — Keflex unilateral stepping as exhibited in an isolated extensor muscle of left 

 knee, the similarly isolated extensor of right knee being relaxed by inhibition while 

 the fellow muscle steps. Decerebrate cat. From same experiment aa fig. 4, but with 



different combined stimulus value, namelv *^ — cm ' . r.p. and l.p., right and left 



" l.p. 16 cm. 



peroneal nerves. Time above in fifths of seconds. Further explanation in text, 

 p. 245. 



intensity of stimulation of the two nerves r. and 1. is answerable for the change 

 from bilateral stepping to unilateral. It suppresses the stepping in the 

 muscle on the same side as the stronger stimulus, and at the same time makes 

 the stepping of the other, the left, muscle faster than it was in fig. 4. It 

 brings this about in the following way. With increase of the strength of the 

 stimulus its ipsilateral inhibition increases more than does its contralateral 

 excitatory effect. When (fig. 4) r. stimulus has a value of 15 cm. it does not 

 suppress the contralateral excitatory effects of 1. stimulits at value 17 cm., but 



