110 Mr. K. Sassa and Prof. C. S. Sherrington. Myogram of the 



a reflex crest-height could be obtained exceeding that of the maximal neuro- 

 myal twitch (2) (6), and with the secondary coil no nearer to the primary for 

 the reflex than for the twitch. To obtain this excess of contraction height 

 above that of maximal twitch the stimulus had always to be much above 

 threshold (4) (7). Under successive increase of the induction-shock stimulus 

 the successive increase of the reflex contraction (flexor) runs a course different 

 from that of the neuromyal twitch. In the latter, as is well known, the 

 maximal twitch is reached soon and then remains constant throughout a long 

 range of further increment of stimulus (maximal stimuli). In the reflex the 

 contraction goes on increasing through a far longer range of stimulus 

 increments ; it is in the upper part of this series that the reflex contraction 

 exceeds the maximal twitch. The result was obtained from any one of the 

 afferent nerves used for the reflex, but most readily from the largest of them, 

 the popliteal in the ham. That the superiority of the height of the contrac- 

 tion excited with the electrodes on the afferent nerve was not due to escape 

 of the current to the motor nerve or muscle, thus adding a twitch contraction 

 to the reflex, was shown by the latent interval of the response remaining of 

 characteristic reflex length (fig. 2). 



(3) Steepness of Ascent. — The ascent of the myogram of the reflex con- 

 traction is not unfrequently for part of its course more steep than is any part 

 of the ascent of the maximal twitch. This tends to occur especially when the 

 crest-height of the reflex is greater than that of the maximal twitch, 



(4) Abruptness of Contraction. — In the myogram of the maximal neuromyal 

 twitch, the vibrations of the recording lever are more evident than in the 

 myogram of the reflex contraction, an indication that the first onset of the 

 pull on the lever is more abrupt in the twitch contraction than in the 

 reflex contraction. Forbes and Gregg (3) pointed out that, in their galvano- 

 metric records of the action-current of the motor nerve, the rise of the 

 current was of sharper development with motor-nerve stimulation than with 

 reflex stimulation. In some experiments we transected the cord several 

 days before the myographic examination. We thought thus to favour the 

 freedom of the flexor reflex by allowing time for subsidence of spinal shock. 

 We found, however, that when a week or more — our longest period was 

 fourteen days — is allowed to elapse after the spinal transection, change 

 ensues in the nerve-muscle preparation itself. The maximal twitch of 

 tibialis anticus, in response to a break-shock applied to its motor nerve, 

 is then feeble and sluggish, of low crest-height, and of abnormally prolonged 

 decline. The duration of the twitch may then be twice or thrice the normal. 

 And in this condition, the reflex contractions, as elicited by a single-shock 

 from afferent nerve or skin, are poor and sluggish, their crest-height 



