Cuar. VIL] NITRATE OF AMMONIA. 128 
movement may have been thus excited; but the corresponding 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 -Jgz 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 in., five marginal tentacles inflected; a second, ten; a third, 
nine marginals and submarginals; and the fourth, twelve, chiefly sub- 
marginals, inflected. After 21 hrs. all these marginal tentacles re- 
expanded, but a few of the submarginals on two of the leaves remained 
slightly 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 ,gPsaq of a grain (°000351 mg.). This ex- 
periment was repeated on three leaves with the same relative amount 
of the solution ; and after 6 hrs. 15 m. all the tentacles 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 0z.), 
so that each received z}, of a grain (°2025 mg.). Before 30 m. had 
elapsed, four of these leaves were immensely, and two of them moder- 
ately, inflected. The glands were rendered of a dark red. The ‘four 
corresponding leaves in water were not at all affected 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 solution of 
one part to 17,500 of water (1 gr. to 40 oz.), 80 that each received ate 
of a grain (‘101 mg.); and in less than 45 m. three of them had al 
their tentacles, except from four to ten, inflected; the blade of oné 
