1913.] arising from Rivalry of Antagonistic Reflexes. 239 



whereas other conditions . . . just miss the natural rhythm of the centres 

 and produce a confused rhythm instead." 



In conformity with this opinion the discrete and regular contractions 

 shown in fig. 1, presenting the appearance of a rhythmic series of wholly 

 separate contractions, which are reciprocals of similar complete relaxations in 

 the fellow muscle, are in reality examples of the above discussed slow form 

 of undulation incident to reflex contraction under concurrent inhibition and 



■2" 



Fig. 2. — Keciproeal stepping of isolated extensor muscle of knees, right and left, refiexly 

 evoked by concurrent stimulation of the antagonistic afferent nerves l.p., left 

 peroneal, and r.p., right peroneal. Decerebrate cat. E.V., right vastocrureus ; 

 L.V., left vastocrureus. Correspondences between the stimulation signals and the 

 myograph events indicated by numerals. The right peroneal stimulation following 

 the left produces the rhythmic though somewhat imperfect stepping, but the left 

 following the right, although the same physical stimuli are employed, fails to do so. 

 Time above in fifths of seconds. 



