112 DROSERA ROTUNDIFOLIA. [Cuap. VII. 
into the solution under trial. The small drop which adhered to it, 
and which was much too small to fall off, was cautiously placed, by 
the aid of a lens, in contact with the secretion surrounding the glands 
of one, two, three, or four of the exterior tentacles of the same leaf. 
Great care was taken that the glands themselves should not be 
touched. I had supposed that the drops were of nearly the same size; 
hut on trial this proved a great mistake. I first measured some water, 
and removed 300 drops, touching the pin’s head each time on blotting- 
paper; and on again measuring the water, a drop was found to equal 
‘on an average about the zy of a minim. Some water in a small vessel 
was weighed (and this is a more accurate method), and 300 drops re- 
moved as before; and on again weighing the water, a drop was found 
to equal on an average only the 4, ofa minim. 1 repeated the opera- 
tion, but endeavoured this time, by taking the pin’s head out of the 
water obliquely and rather quickly, to remove as large drops as 
possible; and the result showed that I had succeeded, for each drop 
on an average equalled +2, of a minim. I repeated the operation in 
exactly the same manner, and now the drops averaged 575 of a 
minim. [Bearing in mind that on these two latter occasions special 
pains were taken to remove as large drops as possible, we may safely 
conclude that the drops used in my experiments were at least equal to 
the 35 of a minim, or ‘0029 c.c. One of these drops could be applied 
to three or even four glands, and if the tentacles became inflected, some 
of the solution must have been absorbed by all; for drops of pure water, 
applied in the same manner, never produced any effect. I was able to 
hold the drop in steady contact with the secretion only for ten to 
tifteen seconds; and this was not time enough for the diffusion of all 
the salt in solution, as was evident, from three or four tentacles treated 
successively with the same drop, often becoming inflected. All the 
inatter in solution was even then probably not exhausted. 
Thirdly.— Leaves were cut off and immersed in a measured quantity 
of the solution under trial; the same number of leaves being im- 
mersed at the same time, in the same quantity of the distilled water 
which had been used in making the solution. ‘The leaves in the two 
lots were compared at short intervals of time, up to 24 hrs., and some- 
times to 48 hrs. They were immersed by being laid as gently as 
possible in numbered watchglasses, and thirty minims (1°775 c.c.) of 
the solution or of water was poured over each. 
Some solutions, for instance that of carbonate of ammonia, quickly 
discolour the glands; and as all on the same leaf were discoloured 
simultaneously, they must all have absorbed some of the salt within 
the same short period of time. This was likewise shown by the 
simultaneous inflection of the several exterior rows of tentacles. If 
we had no such evidence as this, it might have been supposed that 
only the glands of the exterior and inflected tentacles had absorbed the 
salt; or that only those on the disc had absorbed it, and had ther 
transmitted a motor impulse to the exterior tentacles; but in this 
latter case the exterior tentacles would not have become inflected 
