158 DROSERA ROTUXDIFOLIA. Chap. VII. 



after the 8 lirs. it was impossible to compare the two lots, and 

 doubt for an instant the power of the solution. 



Two of the above leaves in the solution had all their tentacles, 

 except three and four, inflected within an hour. I counted their 

 glands, and, on the same principle as before, each gland on one 

 leaf could have absorbed only TTeisoo. and on the other leaf 

 only i^rlooo. of ^ Sixain of the phosphate. 



Twenty leaves were immersed in the usual manner, each in 

 thirty minims of a solution of one part to 218,750 of water (1 gr. 

 to 500 oz.). So many leaves were tried because I was then 

 under the false impression that it was incredible that any 

 weaker solution could produce an effect. Each leaf received 

 _j__ of a grain, or -0081 mg. The first eight leaves which I 

 tried both in the solution and in water were either young and 

 pale or too old ; and the weather was not hot. They were hardly 

 at all affected ; nevertheless, it would be unfair to exclude them. 

 I then waited until I got eight pairs of fine leaves, and the 

 weather was favourable ; the temperature of the room where the 

 leaves were immersed varying from 75° to 81° (23°-8 to 27°-2 

 Cent.). In another trial with four pairs (included in the above 

 twenty pairs), the temperature in my room was rather low, 

 about 60° (15°*5 Cent.) ; but the plants had been kept for several 

 days in a very warm greenhouse and thus rendered extremely 

 sensitive. Special precautions were taken for this set of experi- 

 ments; a chemist weighed for me a grain in an excellent 

 balance ; and fresh water, given me by Professor Frankland, was 

 carefully measured. The leaves were selected from a large 

 niTmber of plants in the followiug manner : the four finest were 

 immersed in water, and the next four finest in the solution, and 

 so on till the twenty pairs were complete. The water specimens 

 were thus a little favoured, but they did not undergo more in- 

 flection than in the previous cases, comparatively with those 

 in the solution. 



Of the twenty leaves in the solution, eleven became inflected 

 within 40 m. ; eight of them plainly and three rather doubt- 

 fully ; but the latter had at least twenty of their outer tentacles 

 inflected. Owing to the weakness of the solution, inflection 

 occurred, except in No. 1, much more slowly than in the pre- 

 vious trials. The condition of the eleven leaves which were 

 considerably inflected will now be given at stated intervals, 

 always reckoning from the time of immersion : — 



(1) After only 8 m. a large number of tentacles inflected, 

 and after 17 m. all but fifteen; after 2 hrs. all but eight in- 



