WATER POACHERS 193 



after dragging it ashore they commenced tearing it 

 up, when they were driven off. It was once thought 

 that both the cormorant and heron only ate that 

 which they could swallow whole, but this is now 

 known not to be strictly correct. 



Ill 



A VEGETABLE POACHER 



ONE of the most curious enemies of our fresh-water 

 fishes is a small floating water-weed, the bladder- 

 wort. Along its branchlets are a number of small 

 green vesicles or bladders, which, being furnished 

 with minute jaws, seize upon tiny fish, which are 

 assimilated into its substance. This is a subtle 

 poacher, the true character of which has only 

 lately been detected. The bladder wort is a fairly 

 common plant, and no very special interest attached 

 to it ere its fish-eating propensities were discovered. 

 Its tiny vesicles were known to contain air, and the 

 only use of these, so far as was known, to keep the 

 plant afloat a belief, be it remarked, all the more 

 reasonable because many aquatic plants actually 

 have such air receptacles for that very purpose. 

 The tiny bladders attached to the leaves and leaf- 

 stalks are each furnished with a door, the whole 

 acting on the eel-trap principle, entrance being 



