126 DROSERA ROTUNDIFOLIA. (Cuar. VII, 
in water. Notwithstanding the care taken and the number of 
the trials made, when in the following year I looked merely 
at the results, without reading over my observations, I again 
thought that there must have been some error, and thirty-five 
fresh trials were made with the weakest solution; but the 
results were as plainly marked as before. Altogether, 106 
carefully selected leaves were tried, both in water and in 
solutions of the phosphate. Hence, after the most anxious 
consideration, I can entertain no doubt of the substantial 
accuracy of my results. 
Before giving my experiments, it may be well to premise that 
crystallised phosphate of ammonia, such as I used, contains 35°33 
per cent. of water of crystallisation; so that in all the following 
trials the efficient elements formed only 64°67 per cent. of the 
salt used. : 
Extremely minute particles of the dry phosphate were placed with 
the point of a needle on the secretion surrounding several glands, 
These poured forth much secretion, were blackened, and ultimately 
died; but the tentacles moved only slightly. The dose, small as it 
was, evidently was too great, and the result was the same as with 
particles of the carbonate of ammonia. 
Half-minims of a solution of one part to 437 of water were placed on 
the discs of three leaves and acted most energetically, causing the 
tentacles of one to be inflected in 15 m., and the blades of all three to 
be much curved inwards in 2 hrs. 15m. Similar drops of a solution 
of one part to 1312 of water (1 gr. to 3 oz.) were then placed on the 
alises of five leaves, so that each received the 5,45 of a grain (0225 mg.). 
After 8 hrs. the tentacles of four of them were considerably inflected, 
and after 24 hrs. the blades of three. After 48 hrs. all five were almost 
jully re-expanded. I may mention with respect to one of these leaves, 
that a drop of water had been left during the previous 24 hrs, on its 
disc, but produced no effect ; and that this was hardly dry when the 
solution was added. 
Similar drops of a solution of one part to 1750 of water (1 gr. to 4 
oz.) were next placed on the discs of six leaves; so that each received 
seao Of a grain (0169 mg.); after 8 hrs. three of them had many 
tentacles and their blades inflected ; two others had only a few tentacles 
Slightly inflected, and the sixth was not at all affected. After 24 hrs, 
most of the leaves had a few more tentacles inflected, but one had 
begun to re-expand. We thus see that with the more sensitive leaves 
the sg45 of a grain, absorbed by the central glands, is enough to make 
many of the exterior tentacles and the blades bend, whereas the +355 
of a grain of the carbonate similarly given produced no effect; and 
seso Of a grain of the nitrate was only just sufficient to produce a well- 
marked effect. 
A minute drop, about equal to 3; of a minim, of a solution of one 
