Chap. Vn.] NITRATE OP AMMONIA. 123 



vessel, and movement may have been thus excited; but the cor- 

 responding leaves in water, which were little inflected, though 

 rather more so than commonly occurs, were exposed in an almost 

 equal degree to these same sources of error. I will, therefore, give 

 only one other experiment made in this manner, though many 

 were tried and all confirmed the foregoing and following results. 

 Four leaves were placed in forty minims of a solution of one part 

 to 10,500 of water; and assuming that they absorbed equally, each 

 leaf received -j-j^y^ of a grain (.0562 mg.). After 1 hr. 20 m. many 

 of the tentacles on all four leaves were somewhat inflected. After 

 5 hrs. 30 m. two leaves had all their tentacles inflected; a third 

 leaf all except the extreme marginals, which seemed old and torpid ; 

 and the fourth a large number. After 21 hrs. every single tentacle, 

 on all four leaves, was closely inflected. Of the four leaves placed 

 at the same time in water, one had, after 5 hrs. 45 m., five mar- 

 ginal tentacles inflected; a second, ten; a third, nine marginals 

 and submarginals ; and the fourth, twelve, chiefly submarginals, 

 inflected. After 21 hrs. all these marginal tentacles re-expanded, 

 but a few of the submarginals on two of the leaves remained slight- 

 ly curved inwards. The contrast was wonderfully great between 

 these four leaves in water and those in the solution, the latter 

 having every one of their tentacles closely inflected. Making the 

 moderate assumption that each of these leaves bore 160 tentacles, 

 each gland could have absorbed only i^^^ia of a grain (.000351 

 mg.). This experiment was repeated on three leaves with the same 

 relative amount of the solution; and after 6 hrs. 15 m. all the ten- 

 tacles except nine, on all three leaves taken together, were closely 

 inflected. In this case the tentacles on each leaf were counted, and 

 gave an average of 162 per leaf. 



The following experiments were tried during the summer of * 

 1873, by placing the leaves, each in a separate watch-glass and 

 pouring over it thirty minims (1.775 c.c.) of the solution; other 

 leaves being treated in exactly the same manner with the doubly 

 distilled water used in making the solutions. The trials .above 

 given were made several years before, and when I read over my 

 notes, I could not believe in the results; so I resolved to begin 

 again with moderately strong solutions. Six leaves were first 

 immersed, each in thirty minims of a solution of one part of 

 the nitrate to 8750 of water (1 gr. to 20 oz.), so that each received 

 y^ of a grain (.2025 mg.). Before 30 m. had elapsed, four of 

 these leaves were immensely, and two of them moderately, in- 

 flected. The glands were rendered of a dark red. The four cor- 

 responding leaves in water were not at all aflfected until 6 hrs. 

 had elapsed, and then only the short tentacles on the borders of 

 the disc; and their inflection, as previously explained, is never of 

 any significance. 



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

 tion of one part to 17,500 of water (1 gr. to 40 oz.), so that each 

 received -g^ of a grain (.101 mg.) ; and in less than 45 m. three 

 of them had all their tentacles, except from four to ten, inflected; 

 the blade of one being inflected after 6 hrs., and the blade of a 



