Cuar. VIL] CARBONATE OF AMMONIA. 117 
We will now turn to the effects of solutions of the carbonate. Half- 
minims of a solution of one part to 437 of water were placed on the discs 
of twelve leaves ; so that each received 545 ofa grain or ‘0675 mg. Ten 
of these had their exterior tentacles well inflected; the blades of some 
being also much curved inwards. In two cases several of the exterior 
tentacles were inflected in 35 m.; but themovement was generally slower. 
‘These ten leaves re-expanded in periods varying between 21 hrs. and 
45 hrs., but in one case not until 67 hrs. had elapsed; so that they 
re-expanded much more quickly than leaves which have caught insects. 
The same-sized drops of a solution of one part to 875 of water were 
placed on the discs of eleven leaves; six remained quite unaffected, 
whilst five had from three to six or eight of their exterior tentacles 
intlected; but this degree of movement can hardly be considered as 
trustworthy. Each of these leaves received sp of a grain (*0337 
mg.), distributed between the glands of the disc, but this was too 
small an amount to produce any decided effect on the exterior tentacles, 
the glands of which had not themselves received any of the salt. 
Minute drops on the head of a small pin, of a solution of one part of 
the carbonate to 218 of water, were next tried in the manner above 
described. A drop of this kind equals on an average ;45 of a minim, 
and therefore contains gsp of a grain (°0135 mg.) of the carbonate. 
1 touched with it the viscid secretion round three glands, so that each 
gland received only ;;19,5 of a grain (*00445 mg.). Nevertheless, in 
two trials all the glands were plainly blackened ; in one case all three 
tentacles were well inflected after an interval of 2 hrs. 40 m.; and in 
another case two of the three tentacles were inflected. I then tried drops 
of a weaker solution of one part to 292 of water on twenty-four glands, 
always touching the viscid secretion round three glands with the same 
little drop. Each gland thus received only the z5455 of a grain 
(°00337 mg.), yet some of them were a little darkened; but in no one 
instance were any of the tentacles inflected, though they were watched 
for 12 hrs. When a still weaker solution (viz. one part to 437 of 
water) was tried on six glands, no effect whatever was perceptible. 
We thus learn that the z;15, of a grain (*00445 mg.) of carbonate of 
ammonia, if absorbed by a gland, suffices to induce inflection in the 
basal part of the same tentacle; but as already stated, I was able to 
hold with a steady hand the minute drops in contact with the 
secretion only for a few seconds; and if more time had been allowed 
ior diffusion and absorption, a much weaker solution would certainly 
have acted. 
Some experiments were made by immersing cut-off leaves in 
solutions of different strengths. Thus four leaves were left for about 
3 hrs. each in a drachm (3°549 c.c.) of a solution of one part of the 
carbonate to 5250 of water; two of these had almost every tentacle 
intlected, the third had about half the tentacles and the fourth about 
one-third inflected; and all the glands were blackened. Another leaf 
was placed in the same quantity of a solution of one part to 7000 of 
water, and in 1 hr. 16 m. every single tentacle was well infected, and 
