How to obtain it. 99 
considerable extent on the amount of nutrition that it can obtain 
through the medium of its vesicles, which form a series of little 
stomachs, both in shape and function, along the branches in the 
axels of the leaves. The walls of the bladders are almost opaque, 
save at the extreme of the posterior end, which is semi-transparent, 
and forms a spot of greenish light. This undoubtedly arouses 
the curiosity of the little perch, which in their anxiety to institute 
further investigations leads them to become entangled on the bifid 
processes, where all further chance of their ever troubling an 
angler is abruptly ended. Care must be exercised in collecting 
the plant for experimental purposes, as a short exposure to the air 
seems to cause the traps of the vesicles to lose their elasticity, 
and renders it valueless for killing purposes. 
The thanks of fish culturists are due to Mr. Simms for 
making known the result of his interesting work, though as far as. 
trout culture is concerned there is probably little fear from the 
presence of bladderwort, beyond the fact that it consumes a 
certain quantity of trout food. In ponds used for coarse fish 
culture, however, the case may be very different, and from these: 
it should be carefully excluded. In the United States, as soon 
as the character of the plant was made known, the late Professor 
Baird issued a circular to American carp culturists warning them 
to remove it from their waters. In ponds such as those of the 
United States Fish Commission at Washington, which I had the 
pleasure of visiting in 1893, such a plant is calculated to do 
harm, for out of the multitudes of small fry which crowd some of 
them, a considerable number would probably fall victims to its 
killing propensities. 
In the ponds at Washington water-plants are largely 
cultivated, and are a most needful part of the system. The ponds. 
are carefully surrounded by fine wire netting to keep out the rats, 
tortoises, water snakes, etc., and are well watched and tended. 
They have proved a most successful part of the work of the 
United States Fish Commission. In some of them the plants on 
which the fish deposit their ova are grown in trays, and when the 
operations are over these trays are lifted out and placed in other’ 
ponds, where the little fish find plenty of food, and are not. 
devoured by their parents. 
