Transmission-time of Reflexes in Spinal Cord of Froc( 83 



the extra delay in the case of the crossed reflex as it appears to have been 

 in each response. It is estimated by the subtraction of the cord delay which 

 is shown to have probably occurred in the case of the immediately preceding 

 or immediately following same-limb reflex response, from the probable 

 cord delay in the case of the crossed reflex. I have indicated, by bracket- 

 ing the lines representing them together, which same-limb reflex response 

 I have employed for the purpose in each case. 



Two of the experiments in which also crossed-reflex responses were 

 obtained, but which do not appear in the tables, may be first referred to. 

 The one [Exp. 38] was one of the four already mentioned (p. 23) as 

 showing no sign of the effect of strychnine in the records, electrical or 

 mechanical, of the same-side reflex responses. It was one in which an 

 extremely minute dose (0"012 mgr.) had been injected only a quarter of an 

 hour before records began to be taken. After two had been taken with 

 the sciatic nerve of the same side as the recording muscle excited, which 

 subsequently showed on measurement that the probable cord delay had 

 been in the two responses respectively 13cr and 14"ocr, a third record was 

 taken with the opposite sciatic nerve excited. A reflex response extremely 

 weak, but lasting about twice as long as when obtained by the excitation of 

 the other nerve, was recorded ; but measurement showed that it did not 

 occur until 83cr after excitation, the cord delay being therefore 634o-(83cr — 

 3"5cr — 1'6(T— 14-5o-) longer than in the simpler reflex. The cro.ssed-reflex 

 response could not be obtained a second time, although three more records, 

 taken when the first nerve was excited, showed that the same-side reflex 

 response was st.ill being obtained unaltered, and with an unaltered probable 

 cord delay, this being respectively in the three : 14"5cr, 14o-, and 13'8o-. 

 From none of the other three preparations, in which, though strychnine 

 had been given, there was no evidence of the fact in the records of the same- 

 side reflex response, could a crossed-reflex response be obtained at all. 



The second experiment, which may be described at once [Exp. 33], was 

 one made on a small frog into which five times as much strychnine had 

 been injected as in the one just mentioned, after the muscle and nerves hlld 

 been prepared and the response without strychnine recorded. Almost 

 immediately after the injection one good record was obtained of the 

 same-side reflex and one of the crossed-reflex response. These are re- 

 produced in fig. 5. The upper curve (A) represents the response when 

 the nerve of the same side was excited. It shows first the response to 

 direct excitation of the motor nerve, which was in this pi-eparation again 

 double, then that to reflex excitation (24-7(r later). The lower curve (B) is 

 the response of the same muscle when the sciatic of the opposite side was 

 excited. The impulse took rather more than twice as long to reach the 

 muscle (54'5o-), but when it began to aflect it, it aftected it much in the 

 same way. There was an unavoidable delay of 10 to 15 minutes before the 

 experiment could be continued. It was then seen that both reflex electrical 

 responses had become serial. Their records showed that both had become 



VOL. 1. — JAN. 1908. 3 



