148 DROSERA ROTUNDIFOLIA. Cuar. VIL 
immersed for a few hours in a solution, and a gland 
absorbs the +s34;55 of a grain (00048 mg.), its colour 
becomes darker, though not actually black; and the 
contents of the cells beneath the gland are plainly 
aggregated. Lastly, under the same circumstances, 
the absorption by a gland of the erys00 Of a grain 
(00024 mg.) suffices to excite the tentacle bearing this 
gland into movement. 
NITRATE OF AMMONIA. 
With the salt I attended only to the inflection of the leaves, 
for it is far less efficient than the carbonate in causing aggrega- 
tion, although considerably more potent in causing inflection. I 
experimented with half-minims (‘0296 ml.) on the discs of fifty- 
two leaves, but will give only a few cases. A solution of one 
part to 109 of water was too strong, causing little inflection, and 
after 24 hrs. killing, or nearly killing, four out of six leaves 
which were thus tried ; each of which received the 71, of a grain 
(or ‘27 mg.). A solution of one part to 218 of water acted most 
energetically, cansing not only the tentacles of all the leaves, 
but the blades of some, to be strongly inflected. Fourteen 
leaves were tried with drops of a solution of one part to 875 
of water, so that the disc of each received the 755 of a grain 
(0337 mg.). Of these leaves, seven were very strongly acted on, 
the edges being generally inflected ; two were moderately acted 
on; and five not at all. 1 subsequently tried three of these latter 
five leaves with urine, saliva, and mucus, but they were only 
slightly affected ; and this proves that they were not in an active 
condition. 1 mention this fact to show how necessary it is to 
experiment on several leaves. ‘Two of the leaves, which were 
well inflected, re-expanded after 51 hrs. 
In the following experiment I happened to select very sensi- 
tive leaves. Half-minims of a solution of one part to 1094 ot 
water (ie. 1 gr. to 25 oz.) were placed on the discs of nine leaves, 
so that each received the 54,5 of a grain (027 mg.). Three of 
them had their tentacles strongly inflected and their blades curled 
inwards; five were slightly and somewhat doubtfully affected, 
having from three to eight of their exterior tentacles inflected : 
one leaf was not at all affected, yet was afterwards acted on by 
saliva. In six of these cases, a trace of action was perceptible in 
