310 



Transactions. 



Table V. 



Control to the above fishes under the same conditions (200 c.c. fluid) 

 showed symptoms of asphyxiation in four hours. 



It was then resolved to compare picrotoxin with tutin in equimoleciilar 

 solutions. The molecular weight of tutin (Ci^HjoOy) is 336, and that of 

 picrotoxin (C4 5HgoOi9) is 887; hence equal weights of tutin and picro- 

 toxin contain by no means the same number of molecules. Accordingly 

 two solutions were prepared, one of 0-005 per cent, tutin and one of 0-0132 



per cent, picrotoxin ( 0-005 x 



887 

 336 



and the experiment was carried out as 



before, three fish (one large, one medium, and one small) being added to 

 each bowl (Exps. 105, 106). The fish in the picrotoxin solution began to 

 show symptoms first. The small fish came to the surface after fifty 

 minutes, and in sixty-five minutes it was on its side. The medium fish also 

 was much excited. In an hour and a half the large fish was found swimming 



