152 DEOSERA ROTUNDIPOLIA. [Chap. VIIL 



flection, and in 3 hre. all the tentacles closely inflected. After 22 

 hrs. still closely inflected; most of the glandH, but not all, black- 

 enal. The leaves were then placed in water; after 24 hr. re- 

 mained 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 of. Three leaves immersed in ninety min- 

 ims of a solution of one part, to 437 of water; in 6 m. some inflec- 

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

 were rather pale. After 24 hrs. all the tentacles still closely in- 

 flected; 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 inflected, and 

 twenty-six had no such effect, two rather doubtful cases oc- 

 curring in each series. In the table at the head of this dis- 

 cussion, 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 impor- 

 tant, 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. 

 We 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 the corresponding salts 

 of potash do not cause inflection, and some of them are 

 poisonous. Two of them, however, viz. the oxalate and iodide 

 of potash, slowly induce a slight and rather doubtful amount 

 of inflection. This difference between the two series is in- 

 teresting, as Dr. Burdon Sanderson informs me that sodium 

 salts may be introduced in large doses into the circulation of 

 mammals without any injurious effects; whilst small doses 

 of potassium salts cause death by suddenly arresting the 

 movements of the heart. An excellent instance of the differ- 

 ent action of the two series is presented by the phosphate of 

 soda quickly causing vigorous inflection, whilst phosphate of 

 potash is quite inefficient. The great power of the former is 

 probably due to the presence of phosphorus, as in the cases of 

 phosphate of lime and of ammonia. Hence we may infer 



