MORGULIS. — DEVELOPMENT OF TOXOPNEUSTES VARIEGATUS. 141 



Experiments with Cocaine Hydrochloride. 



I have not performed as many experiments with cocaine as with 

 some of the other alkaloids, but the effect of cocaine upon the size of 

 larvae can be. inferred even from the rather insufficient data at my 

 disposal. As was also observed in the experiments with other reagents, 

 the influence of cocaine is not revealed during the first day, segmenta- 

 tion going on normally. Even in sea-water containing 2 c.c. of the 

 standard cocaine solution (0.5 per cent aqueous solution) to each 

 100 c.c. gastrulae may appear at the same time as in the control, and 

 they are in all essentials normal. In sea-water with i to 1 c.c. of the 

 cocaine solution per 100 c.c. the plutei are invariably from £ to \ 

 smaller than the normal ones. But in weaker concentrations (\ to 

 \ c.c. of a 0.5 per cent solution of cocaine to 100 c.c. of sea-water), 

 though the size of the plutei may be slightly reduced, there is consid- 

 erable variation in size between the plutei of different lots of eggs. 

 It may be assumed, however, that the limit of toxicity of the cocaine 

 is probably i to ^ c.c. of a 0.5 per cent solution to 100 c.c. of 

 sea-water. 



Experiments with Strychnine. 



The sulphate of strychnine was used in a 0.5 per cent aqueous 

 solution. As in all foregoing experiments no effect has been observed 

 upon segmenting eggs in sea-water to which from ^ 5 c.c. to 1 c.c. of 

 the strychnine solution was added. The blastula stage is reached at 

 the same time in all the several concentrations. But from this stage 

 on the influence of the poison becomes quite pronounced in the stronger 

 solutions, where fewer larvae come to the surface, and where also the 

 process of gastrulation lags behind that of the control. The limit of 

 toxicity of strychnine differs for eggs of different animals, but ^\ c.c. 

 of the standard solution (0.5 per cent) diluted in 100 c.c. of sea-water 

 is invariably ineffective. The plutei developed in various strychnine 

 solutions ( T V c.c. to 1 c.c.) are smaller than normal ones ; the differ- 

 ences, however, are not constant, being greater or smaller in different 

 sets of eggs, as was also the case in experiments with all other reagents. 

 Table V contains the records of one of the experiments. 



From this table it can be seen that as the strychnine solution reaches 

 an effective concentration, it also causes a reduction of the size of 

 the larvae, although the early stages in the development are not in the 

 least modified. 



