ransmission 



■time of Reflexes in Spinal Cord of Frog 



21 



of strychnine ; then of those of the second gastrocnemius when the second 

 sciatic nerve was stimulated after the administration of strychnine in 

 sufficient quantity, and for a long enough time to make the contraction in 

 response to a single break induction shock to the mixed nerve something 

 stronger than a twitch. Exp. 14, which has already been referred to (p. 8), 

 and of which one of the records obtained when the cord was normal has 

 been reproduced in fig. 2, A, is perhaps the most valuable of these, for the 

 reason that the cord was only excited four times, and gave an excellent 

 response each time, before the administration of the drug, and that as 

 many as nine equally good reflex responses were recorded with the other 

 muscle after its administration. In seven of these it occurred in almost 

 exactly the same time after the direct response, and in all seven the interval 

 was from la to l|o- less than in any of the responses obtained from the 

 same cord without strychnine. In the other two responses it was shorter 

 still, but in these two (both of which, as it happened, were to stronger 

 stimuli after weaker ones) the eflect, when it began, instead of being strong, 

 was very weak, and it only became maximal, in the one case (fourth 

 response) 2ar, and in the other (seventh response) 4(t, later. 



The following table gives the data for both parts of the experiment : — 



Exp. 14. Oct. 1, 1906. Room temp. 18° C. Records taken first with 

 the right gastrocnemius to excitation of the right sciatic. Cord normal. 



Induction current 

 to nerve. 



Strength. 



Length, in millimetres, of 



Time, in thousandths of a second (<r). 



muscle 

 from en- 

 trance of 

 nerve to i). 



nerve 

 from Cw 

 electrode 

 to muscle. 



taken by 



interval 

 between 



to be de- 

 ducted 



electrode 

 to cord. 



reach p direct and 

 directly of reflex 



^(measured). effecUa^t^p (,3,^,,). 



in nerve 



delay in 

 cord. 



2-6 ' 19-5 2 17-5 



2-6 15-6 2 13-6 



2-6 18 1-8 16-2 



2-6 19 2 ' 17 



5,000 d 7 14 



10,000 \ d 7 14 



10,000 \ a 7 17 



10,000 \ d 7 14 30 



Records then taken with the left gastrocnemius to excitation of the left 

 sciatic, prepared a quarter of an • hour after the injection of ^ minim 

 0-1 per cent. liq. strych. into the dorsal lymph sac. 



