Chap. VII.] PHOSPHATE OF AMMONIA. 131 



ception of four, were inflected after 24 hrs., but none of them 

 closely; the blade was also inflected; each gland could have re- 

 ceived only the is T iggo of a grain, or .0000387 mg. Lastly, leaf 

 No. 11, which had after 24 hrs. all its tentacles, except one, closely 

 inflected, as well as the blade, bore the unusually large number of 

 252 tentacles; and, on the same principle as before, each gland 

 could have absorbed only the ;o oi u ffo of a grain, or .0000322 mg. 



With respect to the following experiments, I must premise that 

 the leaves, both those placed in the solutions and in water, were 

 taken from plants which had been kept in a very warm greenhouse 

 during the winter. They were thus rendered extremely sensitive, 

 as was shown by water exciting them much more than in the 

 previous experiments. Before giving my observations, it may be 

 well to remind the reader that, judging from thirty-one fine leaves, 

 the average number of tentacles is 192, and that the outer or ex- 

 terior ones, the movements of which are alone significant, are to 

 the short ones on the disc in the proportion of about sixteen to 

 nine. 



Four leaves were immersed as before, each in thirty minims of 

 a solution of one part to 328,125 of water (1 gr. to 750 oz.). Each 

 leaf thus received jgo ^ ooo of a grain (.0054 mg.) of the saltr and all 

 four were greatly inflected. 



( 1 ) After 1 hr. all the outer tentacles but one inflected, and the 

 blade greatly so; after 7 hrs. began to re-expand. 



(2) After 1 hr. all the outer tentacles but eight inflected; after 

 12 hrs. all re-expanded. 



(3) After 1 hr. much inflection; after 2 hrs. 30 m. all the 

 tentacles but thirty-six inflected; after 6 hrs. all but twenty-two 

 inflected; after 12 hrs. partly re-expanded. 



(4) After 1 hr. all the tentacles but thirty-two inflected; after 

 2 hrs. 30 m. all but twenty-one inflected; after 6 hrs. almost re- 

 expanded. 



Of the four corresponding leaves in water: 



(1) After 1 hr. forty-five tentacles inflected; but after 7 hrs. so 

 many had re-expanded that only ten remained much inflected. 



(2) After 1 hr. seven tentacles inflected; these were almost re- 

 expanded in 6 hrs. 



(3) and (4) Not aflfected, except that, as usual, after 11 hrs. 

 the short tentacles on the borders of the disc fcrme<l a ring. 



There can, therefore, be no doubt about the efficiency of the 

 above solution; and it follows as before that each gland of No. 1 

 could have absorbed only y^riTnnr of a grain (.0000208 mg.) and 

 of No. 2 only r^oims of a grain (.0000263 mg.) of the phosphate. 



Seven leaves were immersed, each in thirty minims of a solu- 

 tion of one part to 437,500 of water (1 gr. to ioOO oz.). Each leaf 

 thus received i-eoinr of a grain (.00405 mg.). The day was warm, 

 and the leaves were very fine, so that all circumstances were 

 favourable. 



(1) After 30 m. all the outer tentacles except five inflected, and 

 10 



