Chap. XVII. ABSOKPTION 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 

 blotting paper and gently pressed, water oozes out. 



