How to obtain it. 99 



siderable 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 

 axils 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. 



