186 DROSEKA ROTUNDIFOLIA. Chap. YIU. 



of a solution of one part to 437 of water ; after 2 hrs. some inflec- 

 tion ; after 3 hrs. 45 m. tentacles closely inflected, with the 

 glands blackened. After 22 lu's. still closely inflected, and the 

 leaves flaccid. Placed in pure water, next day evidently dead. 

 A rapid poison. 



Nick'^^1, Chloride of. — Tliree leaves immersed in ninety minims 

 of a solution of one part to 437 of water ; in 25 m. considerable 

 inflection, and in 3 hi's. all the tentacles closely inflected. After 

 22 hrs. still closely inflected; most of the glands, but not all, 

 blackened. The leaves were then placed in water ; after 24 hrs. 

 remained inflected ; were somewhat discoloured, with the glands 

 and tentacles dingy red. Probably killed. 



Cobalt, Chloride of. — Three leaves immersed in ninety minims 

 of a solution of one part to 437 of water ; after 23 hrs. there 

 was not a trace of inflection, and the glands were not more 

 blackened than often occurs after an equally long immersion in 

 water. 



Platinum., Chloride o/.— Three leaves immersed in ninety 

 minims of a solution of one part to 437 of water ; in 6 m. some 

 inflection, which became immense after 48 m. After 3 hrs. the 

 glands were rather pale. After. 24 hrs. all the tentacles still 

 closely inflected; glands colourless; remained in same state for 

 four days; leaves evidently killed. 



Concluding Remarks on the Action of the foregoing 

 Salts. — Of the fifty-one salts and metallic acids which 

 were tried, twenty-five caused the tentacles to be in- 

 flected, and twenty-six had no such effect, two rather 

 doubtful cases occurring in each series. In the table 

 at the head of this discussion, the salts are arranged 

 according to their chemical affinities ; but their action 

 on Drosera does not seem to be thus governed. The 

 nature of the base is far more important, as far as can 

 be judged from the few experiments here given, than 

 that of the acid ; and this is the conclusion at which 

 physiologists have arrived with respect to animals. 

 AVe see this fact illustrated in all the nine salts of 

 soda causing inflection, and in not being poisonous 

 except when given in large doses ; whereas seven of 



