128 DROSERA ROTUNDIPOLIA. [Chap. Vn. 



three out of the eighteen were only slightly affected, having 

 twenty-one, nineteen, and twelve tentacles inflected ; and one was 

 not at all acted on. By an accident only fifteen, instead of 

 eighteen leaves were immersed at the same time in water; these 

 were observed for 24 hrs.; one had six, another four, and a third 

 two, of their outer tentacles inflected; the remainder being quite 

 unafTected. 



The next experiment was tried under very favourable circum- 

 stances, for the day (July 8) was very warm, and I happened to 

 have unusually fine leaves. Five were immersed as before in a 

 solution of one part to 131,250 of water (1 gr. to 300 oz.), so that 

 each received ts^ot o^ * gi'^iinj or .0135 mg. After an immersion of 

 25 m. all five leaves were much inflected. After 1 hr, 25 m. 

 one leaf had all but eight tentacles inflected; the second, all 

 but three; the third, all but five; the fourth, all but twenty-three; 

 the fifth, on the other hand, never had more than twenty-four in- 

 flected. Of the corresponding five leaves in water, one had seven, 

 a second two, a third ten, a fourth one, and a fifth none inflected. 

 I^et it be observed what a contrast is presented between these latter 

 leaves and those in the solution. I counted the glands on the 

 second leaf in the solution, and the number was 217; assuming 

 that the three tentacles which did not become inflected absorbed 

 nothing, we find that each of the 214 remaining glands could have 

 absorbed only rnrfnnj of a grain, or .0000631 mg. The third leaf 

 bore 23G glands, and subtracting the five which did not become 

 inflected, each of the remaining 231 glands could have absorbed 

 only itfllgoo of a grain (or .0000584 mg.), and this amount suf- 

 ficed to cause the tentacles to bend. 



Twelve leaves were tried as before in a solution of one part to 

 175,000 of water (1 gr. to 400 oz.), so that each leaf received -g^fni 

 of a grain (.0101 mg.). My plants were not at the time in a good 

 state, and many of the leaves were young and pale. Nevertheless, 

 two of them had all their tentacles, except three or four, closely in- 

 flected in under 1 hr. Seven were considerably affected, some 

 within 1 hr., and others not until 3 hrs., 4 hrs. 30 m., and 8 hrs. had 

 elapsed; and this slow action may be attributed to the leaves be- 

 ing young and pale. Of these nine leaves, four had their blades 

 well inflected, and a fifth slightly so. The three remaining leaves 

 were not affected. With respect to the twelve corresponding leaves 

 in water, not one had its blade infleoto<l; after from I to 2 hrs. one 

 had thirteen of its outer tentacles inflected; a second six, and four 

 others either one or two inflected. After 8 hrs. the other tentacles 

 did not become more inflected ; whereas this occurred with the 

 leaves in the solution. I record in my notes that after the 8 hrs. 

 it was impossible to compare the two lots, and doubt tor 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 plnnd on one 

 leaf could have absorbed only riiiTrnr* "^^^ ^^ ^^^ other leaf only 

 TTrWa of a grain of the phosphate. 



