264 ALDROVANDA VESICULOSA. (Cuar. XIV. 
was no change, but when next examined after 23 hrs. 20 m., 
the outer cells of the glands contained, instead of limpid 
fluid, spherical masses of a granular substance, showing that 
matter had been absorbed from the infusion. That these 
glands secrete a fluid which dissolves or digests animal 
matter out of the bodies of the creatures which the leaves 
capture, is also highly probable from the analogy of Dionza. 
If we may trust to the same analogy, the concave and inner 
portions of the two lobes probably close together by a slow 
movement, as soon as the glands have absorbed a slight 
amount of already soluble animal matter. The included 
water would thus be pressed out, and the secretion conse- 
quently not be too much diluted to act. With respect to 
the quadrifid processes on the outer parts of the lobes, I was 
not able to decide whether they had been acted on by the 
infusion ; for the lining of protoplasm was somewhat shrunk 
before they were immersed. Many of the points on the 
infolded rims also had their lining of protoplasm similarly 
shrunk, and contained spherical granules of hyaline matter. 
A solution of urea was next employed. This substance 
was chosen partly because it is absorbed by the quadrifid 
processes and more especially by the glands of Utricularia— 
a plant which, as we shall hereafter see, feeds on decayed 
animal matter. As urea is one of the last products of the 
chemical changes going on in the living body, it seems fitted 
to represent the early stages of the decay of the dead body. I 
was also led to try urea from a curious little fact mentioned 
by Prof. Cohn, namely that when rather large crustaceans 
are caught between the closing lobes, they are pressed so 
hard whilst making their escape that they often void their 
sausage-shaped masses of excrement, which were found 
within most of the leaves. These masses, no doubt, contain 
urea. They would be left either on the broad outer surfaces 
of the lobes where the quadrifids are situated, or within the 
closed concavity. In the latter case, water charged with 
excrementitious and decaying matter would be slowly forced 
outwards, and would bathe the quadrifids, if I am right in 
believing that the concave lobes contract after a time like 
those of Dionza. Foul water would also be apt to ooze out 
at all times, especially when bubbles of air were generated 
within the concavity. 
A leaf was cut open and examined, and the outer cells of 
the glands were found to contain only limpid fluid. Some 
