Tartrate of Ammonia. Half-minims of a solution of one part to 437 of
water were placed on the discs of five leaves. In 31 m. there was a
trace of inflection in the exterior tentacles of some of the leaves,
and this became more decided after 1 hr. with all the leaves; but the
tentacles were never closely inflected. After 8 hrs. 30 m. they began
to re-expand. Next morning, after 23 hrs., all were fully re-expanded,
excepting one which was still slightly inflected. The shortness of the
period of inflection in this and the following case is remarkable.
Chloride of Ammonium. Half-minims of a solution of one part to 437 of
water were placed on the discs of six leaves. A decided degree of
inflection in the outer and submarginal tentacles was perceptible in 25
m.; and this increased during the next three or four hours, but never
became strongly marked. After only 8 hrs. 30 m. the tentacles began to
re-expand, and by the next morning, after 24 hrs., were fully
re-expanded on four of the leaves, but still slightly inflected on
two.]
General Summary and Concluding Remarks on the Salts of Ammonia. We have
now seen that the nine [page 168] salts of ammonia which were tried,
all cause the inflection of the tentacles, and often of the blade of
the leaf. As far as can be ascertained from the superficial trials with
the last six salts, the citrate is the least powerful, and the
phosphate certainly by far the most. The tartrate and chloride are
remarkable from the short duration of their action. The relative
efficiency of the carbonate, nitrate, and phosphate, is shown in the
following table by the smallest amount which suffices to cause the
inflection of the tentacles.
Column 1 : Solutions, how applied. Column 2 : Carbonate of Ammonia.
Column 3 : Nitrate of Ammonia. Column 4 : Phosphate of Ammonia.
Placed on the glands of the disc, so as to act indirectly on the outer
tentacles : 1/960 of a grain, or 0675 mg. : 1/2400 of a grain, or .027
mg. : 1/3840 of a grain, or .0169 mg.
Applied for a few seconds directly to the gland of an outer tentacle :
1/14400 of a grain, or .00445 mg. : 1/28800 of a grain, or .0025 mg.
grain, 1/153600 of a grain, or .000423 mg.
150