166 DROSERA ROTUNDIFOLIA. Cuap. VIL 
absorbed only s57dso50 Of a grain, or ‘00000328 mg.; and this 
excessively minute amount sufficed to cause all the tentacles 
bearing these glands to be greatly inflected. The blade was also 
inflected. 
Summary of the Results with Phosphate of Ammonia.— 
The glands of the disc, when excited by a half-minim 
drop (0296 ml.), containing 5,4, of a grain (‘0169 
mg.) of this salt, transmit a motor impulse to the 
exterior tentacles, causing them to bend inwards. A 
minute drop, containing +5350 of a grain (000423 
mg.), if held for a few seconds in contact with a 
gland, causes the tentacle bearing this gland to_be 
inflected. If a leaf is left immersed for a few hours, 
and sometimes for a shorter time, in a solution so 
weak that each gland can absorb only the +,-s005 
of a grain (00000328 mg.), this is enough to excite 
the tentacle into movement, so that it becomes 
closely inflected, as does sometimes the blade. In 
the general summary to this chapter a few remarks 
will be added, showing that the efficiency of such 
extremely minute doses is not so incredible as it 
must at first appear. : 
Sulphate of Ammonia.—The few trials made with this and the 
following five salts of ammonia were undertaken merely to 
ascertain whether they induced inflection. Half-minims of a 
“solution of one part of the sulphate of ammonia to 487 of 
water were placed on the discs of seven leaves, so that each 
received 53, of a grain, or ‘0675 mg. After 1 hr. the tentacles 
of five of them, as well as the blade of one, were strongly 
inflected. ‘he leaves were not afterwards observed. 
Citrate of Ammoniu.—Half-minims of a solution of one part 
to 487 of water were placed on the discs of six leaves. In 
l hr. the short outer tentacles round the discs were a little 
inflected, with the glands on the discs blackened. After 
3 hrs. 25 m. one leaf had its blade inflected, but none of the 
exterior tentacles, All six leaves remained in nearly the same 
state during the day, the submarginal tentacles, however, 
