Ouse. XVI. ABSORPTION BY THE GLANDS. 417 
long kept in moderately pure water, are colourless; 
and their primordial utricles are only slightly or 
hardly at all granular. But in the greater number of 
plants in a state of nature—and we must remember 
that they generally grow in very foul water —and 
with plants kept in an aquarium in foul water, most 
of the glands were of a pale brownish tint; their prim- 
ordial utricles were more or less shrunk, sometimes 
ruptured, with their contents often coarsely granular 
or aggregated into little masses. That this state of 
the glands is due to their having absorbed matter from 
the surrounding water, I cannot doubt; for, as we shall 
immediately see, nearly the same results follow from 
their immersion for a few hours in various solutions. 
Nor is it probable that this absorption is useless, 
seeing that it is almost universal with plants growing 
in a state of nature, excepting when the water is re 
markably pure. 
The pedicels of the glands which are situated close 
to the slit-like orifice, both those on the valve and on 
the collar, are short; whereas the pedicels of the more 
distant glands are much elongated and project inwards. 
The glands are thus well placed so to be washed by 
any fluid coming out of the bladder through the. 
orifice. The valve fits so closely, judging from the 
result of immersing uninjured bladders in various 
solutions, that it is doubtful whether any putrid fluid 
habitually passes outwards. But we must remember 
that a bladder generally captures several animals; and 
that each time a fresh animal enters, a puff of foul 
water must pass out and bathe the glands. Moreover, 
I have repeatedly found that, by gently pressing blad- 
ders which contained air, minute bubbles were driven 
out through the orifice; and if a bladder is laid on 
plotting paper and gently pressed, water oozes out. 
