136 SALMON -AND TROUT. 



to one of those mouse traps in which a small door closes behind 

 the unsuspecting mouse as soon as he has entered. Mrs. Treat, of 

 New Jersey, first showed that these bladders were really insecti- 

 vorous or carnivorous organs ; and Mr. Darwin afterwards worked 

 out the subject in minute detail, recording the results of his obser- 

 vations in his charming volume on Insectivorous Plants. He showed 

 that small floating animals, such as fresh-water shrimps or the 

 larvae of gnats, get entangled in the bladders, and there die, their 

 decomposing bodies afterwards serving as food for the tissues of 

 the plant. So far as he could discover, no true secretion of the 

 nature of a gastric juice takes place inside the bladders, and so 

 there is no true digestion, as in some of the higher and more per- 

 fect insect-eating plants, such as the sundew ; but the wall of the 

 bladder is covered by small glands, and by prickly hairs ' a ser- 

 ried mass of processes,' as Darwin well calls them, which absorb 

 directly the protoplasm or valuable organic matter of the included 

 prey into the tissues of the hungry bladderwort. Darwin believed 

 that the fresh-water shrimps and other creatures on which the 

 bladderwort feeds merely entered the door of the bladder out of 

 pure curiosity, so to speak, without the plant making any definite 

 quasi-voluntary efforts to entice or entrap them ; but Mrs. Treat's 

 more recent investigations seem rather to show that the tiny vege- 

 table traps actually open their mouths automatically, and snap up 

 the unwary prey whenever it approaches too near the small green 

 and almost invisible jaws. It should be added that the statement 

 recently made in several newspapers as to the bladders being ' the 

 size of a pear' is an obvious mistake. If Utricularia were a carni- 

 vorous plant on such a gigantic scale as that, it would prove a very 

 parlous fish eater indeed, and be hunted down by salmon preservers 

 like otters and herons. The real size of the bladders is scarcely 

 that of a garden poppy seed. 



At this stage our knowledge of the habits and manners of the 

 bladderwort rested until the spring of the past year. The plant 

 was known to catch small insects and fresh-water crustaceans in its 

 tiny traps, and to use up their bodies as manure for its own de- 

 velopment ; but it was not yet known to be distinctly piscivorous. 

 Last May, however, Mr. G. E. Simms of Oxford, brought Professor 

 Moseley a specimen of Utricularia in a glass bowl, in which were 

 numbers of young roach, just hatched out of a mass of spawn lying 

 at the bottom. Many of the small fry were seen dead, held fast in the 

 firm bladder jaws of the murderous plant. Professor Moseley, being 



