218 DROSERA ROTUNDIFOLIA. [Cuap, XI. 
‘salts of ammonia. These all cause the tentacles, and often 
the blade of the leaf, to be inflected, and the protoplasm to 
be, aggregated. They act with very different power; the 
citrate being the least powerful, and the phosphate, owing, 
no doubt, to the presence of phosphorus and nitrogen, by far 
the most powerful. But the relative efficiency of only three 
salts of ammonia was carefully determined, namely the car- 
bonate, nitrate, and phosphate. The experiments were made 
by placing half-minims (-0296 c.c.) of solutions of different 
strengths on the discs of the leaves,—by applying a minute 
drop (about the 3, of a minim, or :00296 c.c.) for a few 
seconds to three or four glands,—and by the immersion of 
whole leaves in a measured quantity. In relation to these 
experiments it was necessary first to ascertain the effects of 
distilled water, and it was found, as described in detail, that 
the more sensitive leaves are affected by it, but only ina 
slight degree, 
A solution of the carbonate is absorbed by the roots and 
induces aggregation in their cells, but does not affect the 
leaves. The vapour is absorbed by the glands, and causes 
inflection as well as aggregation. A drop of a solution con- 
taining ,}, of a grain (-0675 mg.) is the least quantity 
which, when placed on the glands of the disc, excites the 
exterior tentacles to bend inwards. Buta minute drop, con- 
taining ygigq of a grain (*00445 mg.), if applied for a few 
seconds to the secretion surrounding a gland, causes the 
inflection of the same tentacle. When a highly sensitive 
leaf is immersed in a solution, and there is ample time for 
absorption, the s¢ggqq Of a grain (°00024 mg.) is sufficient 
to excite a single tentacle into movement. 
The nitrate of ammonia induces aggregation of the 
protoplasm much less quickly than the carbonate, but is 
more potent in causing inflection. A drop containing ~5 
of a grain (-027 mg.) placed on the disc acts powerfully 
on all the exterior tentacles, which have not themselves 
received any of the solution ; whereas a drop with gqy_ of a 
grain caused only a few of these tentacles to bend, but 
affected rather more plainly the blade. A minute drop ap- 
plied as before, and containing z,1,, of a grain (+0025 mg.), 
caused the tentacle bearing this gland to bend. By the 
immersion of whole leaves, it was proved that the absorp- 
tion by a single gland of gypegp of a grain (-0000937 mg.) 
‘was sufficient to set the same tentacle into movement. 
