334 INHIBITION BY EXCITATION AND 



depends probably upon an ' intensification of the process of excita- 

 tion beyond the normal amount.' 



It is unnecessary to give an exact description of the vari- 

 ations in the contraction curve caused by veratrine poison- 

 ing, because a detailed examination of them is found in many 

 works, and I have nothing essentially novel to add. I shall there- 

 fore limit myself here to a brief discussion of the method of 

 poisoning which showed itself best suited to my purpose in the 

 course of the investigation. As it was of the first importance to 

 me to obtain a strong contraction of the whole transverse section of 

 the sartorius, and especially that this should last as long as possible, 

 the most appropriate way seemed to be to poison the whole animal ; 

 thus the only question was to find the most suitable dose on the 

 one hand, and on the other to determine the point of time which 

 should be considered the most favourable for the preparation of the 

 muscle. 



The extraordinary sensitiveness of the muscle of the frog for 

 minimal amounts of the poison introduced through the blood, 

 made me refrain for a long time from using stronger doses, because 

 I feared a too rapid decrease of excitability. However, in the end, 

 the use of larger amounts with a shorter period of action proved 

 to be best. As some of the experiments took place at the begin- 

 ning of the warm season, when the muscles of Rana esculenta are 

 little suited on the whole for electro-physiological experiments as 

 I had found from previous experience, I used later almost exclusively 

 the muscles of K/. temporaria. I had no ground for regret on this 

 account, for they proved to be much more excitable, and are 

 therefore better for the purpose than those of R. esculenta even 

 at the most favourable season of the year. 



Although, as Kolliker has already shown, a previous administra- 

 tion of curare is not sensibly prejudicial to the action of veratrine, 

 I confined myself as a rule to the use of the latter poison alone, 

 because certain appearances of movement which present themselves 

 in the muscles of the poisoned animal, enable one to recognise the 

 proper stage of the action of the poison with the greatest certainty. 

 However, I assured myself every time by special control experi- 

 ments, that the results of the experiments about to be described are 

 in no way prejudicially affected by the simultaneous use of curare. 



I introduced as a rule 6-7 drops of a I % solution of acetate of 

 Veratrine into the dorsal lymph sac, and killed the frog 10 minutes 

 afterwards at latest. Generally 5-7 minutes suffice to produce 



