302 THE BEHAVIOUR OF HYLA AUREA TO STRYCHNINE 



From this Table it appears that the muscle immersed in strychnine 

 retained its excitability until the end of the observation (72 

 minutes), although after 12 minutes the muscle could no longer 

 be stimulated through the nerve. When the nerve was immersed 

 in the solution, little change in excitability was noticeable even 

 after 72 minutes. The seven other experiments showed con- 

 cordant results with the one recorded. The muscle immersed in 

 the solution of strychnine ceased to be excited through the nerve 

 in 11, 15, 27, 26, 21, 51 and 53 minutes respectively. 



A second series was carried out with a solution of 1 part of 

 strychnine as sulphate in 1000 parts of normal saline solution. 

 Nine experiments were performed. Results were obtained 

 similar to those with a 1 in 10,000 solution of strychnine. After 

 a varying interval the muscle immersed in the poison ceased to 

 be excitable through the nerve. This point was reached in 36, 42, 

 42, 30, 18, 24, 28, 18 and 21 minutes respectively. It is note- 

 worthy that increase in the concentration of strychnine ten-fold 

 did not diminish the period in which the receptive substance of 

 the muscle was paralysed. If these results are compared with 

 those observed in the living entire frog it is noted that, with doses 

 greater than 0*05 mg. per gm. body-weight, paralysis results in 

 less than 15 minutes. In other words, with a possible concen- 

 tration of 1 in 20,000 in the tissues the receptive substance is 

 rendered inexcitable through the nerve-endings. With possible 

 concentrations of 1 in 10,000 and 1 in 5,000 the paralysis is 

 complete in 5 minutes. The absorption of a considerable quantity 

 of strychnine is probably a matter of hours. As yet no measure- 

 ments have been made concerning the rate at which the strych- 

 nine leaves the dorsal lymph sac. It is, however, evident that a 

 very much lower concentration than 1 in 20,000 in the tissues is 

 adequate when brought in efficient contact with the receptive 

 substance by means of extra-capillary lymph, to paralyse the 

 receptive substance, or that the receptive substance possesses an 

 affinity for strychnine whereby the concentration of strychnine 

 in the receptive substance is raised above that in the remainder 

 of the tissues. 





