Cuap. VII] CARBONATE OF AMMONIA. 119 
Ammonia.—I have fully described in the third chapter the remarkable 
effects of moderately strong doses of this salt in causing the aggre- 
gation of the protoplasm within the cells of the glands and tentacles ; 
and here my object is merely to show what small doses suffice. A 
leaf was immersed in twenty minims (1°183 ¢.c.) of a solution of one 
part to 1750 of water, and another leaf in the same quantity of a 
solution of one part to 8062; in the former case aggregation occurred 
in 4 m., in the latter in 11m. A leaf was then immersed in twenty 
minims of a solution of one part to 4375 of water, so that it received 
win of a grain (27 mg.); in 5 m. there was a slight change of colour 
in the glands, and in 15 m. small spheres of protoplasm were formed in 
the cells beneath the glands of all the tentacles. In these cases there 
could not be a shadow of a doubt about the action of the solution. 
A solution was then made of one part to 5250 of water, and I 
experimented on fourteen leaves, but will give only a few of the cases. 
Hight young leaves were selected and examined with care, and they 
showed no trace of aggregation. Four of these were placed in a 
drachm (3°549 c.c.) of distilled water; and four in a similar vessel, 
with a drachm of the solution. After a time the leaves were examined 
under a high power, being taken alternately from the solution and the 
water. ‘The first leaf was taken out of the solution after an immersion 
of 2 hrs. 40 m., and the last leaf out of the water after 3 hrs. 50 m.; 
the examination lasting for 1 hr. 40m. In the four leaves out of the 
water there was no trace of aggregation except in one specimen, in 
which a very few extremely minute spheres of protoplasm were present 
beneath some of the round glands. All the glands were translucent 
and red. The four leaves which had been immersed in the solution, 
besides being inflected, presented a widely different appearance; for 
the contents of the cells of every single tentacle on all four leaves were 
conspicucusly aggregated; the spkeres and elongated masses of proto- 
plasm in many cases extending halfway down the tentacles. All the 
glands, both those of the central and exterior tentacles, were opaque 
and blackened; and this shows that all had absorbed some of the 
carbonate. These four leaves were of very nearly the same size, and the 
glands were counted on one and found to be 167. This being the case, 
and the four leaves having been immersed in a drachm of the solution, 
each gland could have received on an average only gylyz5 of a grain 
(*001009 mg.) of the salt : and this quantity sufficed to induce within 
a short time conspicuous aggregation in the cells. beneath all the glands. 
A vigorous but rather small red leaf was placed in six minims of the 
same solution (viz. one part to 5250 of water), so that it received =25 
of a grain (-0675 mg). In 40 m. the glands appeared rather darker ; 
and in 1 hr. from four to six spheres of protoplasm were formed in the 
cells beneath the glands of all: the tentacles. I did not count the 
tentacles ; but we may safely assume that there were at least 140; and 
if so, each gland could have received only the zyZyo5 Of a grain, or 
“00048 mg. 
A weaker solution was then made of one part to 7000 of water, and 
