98 How to obtain tt. 
Mr. G. E. Simms, of Oxford, who had the plant growing in an 
aquarium in which the fry of perch and roach were also kept. 
Seeing some little fish apparently lying dead amongst the 
bladderwort, Mr. Simms endeavoured to remove them, and found 
that they were firmly held by the plant. The latter may be 
briefly described as a floating species growing in ditches, ponds, 
and other still waters. The stem lies in a somewhat prostrate 
position, from which numerous thread-like leaves grow out in 
whorls. Amongst these leaves are found a number of tiny 
vesicles, which were formerly supposed to be air-bladders by 
means of which the plant floated to the surface. These now 
come out in their true character as traps for living creatures, 
including fish, upon which the plant probably feeds. The 
vesicles are somewhat pear-shaped, and possess an opening at 
the smaller end which is closed by a valve. This valve opens on 
pressure from without, and closes upon any unfortunate creature 
that may enter. Young fish have been found caught by the head, 
tail, and umbilical sac. Crustaceans, larvae, entomostraca, etc.,. 
are entrapped by these vesicles or so called bladders, from which 
the plant derives its name. In summer it sends up a flower stem 
some five or six inches high. The blossoms are yellow streaked 
with purple. 
Mr. Simms tells me that experiments have shewn that it is 
very seldom, indeed, that young roach become entangled in the 
bifid processes with which the quadrangular mouth of the vesicle 
is furnished; young perch, however, succumb freely to its 
influence, which is a purely mechanical one. Under a high 
power microscope, the vesicles appear perfectly smooth and 
polished, and they seem to be armed with a series of reversed 
serrations, pointing towards the opening. These serrations catch 
the delicate skin of the fry, whose every struggle only sends them 
further on towards the opening, and so on until the posterior wall 
of the vesicle is reached, when the fish is prevented from making 
its exit by the closing of the trap. Sooner or later the fish dies, 
decomposition sets in, the tail drops off, that is, as much of it as. 
is exposed outside the vesicle, whilst the protoplasm engendered 
by the decomposition of the portion within, is utilised for the 
support of the plant. Having no root, it is dependent to a 
