imiTISII SPECIES OP UTKICULARIA. ,S;3 



causing them to float on the surface of the water." In \SC)^ a ^Fr 

 Holland announced that he had observed minute water insects in 

 the bladders ; this led Charles Darwin to study their uses and 

 structure with great care, and the results of his observations were 

 published in his "Insectivorous Plants" in 1875, he being just 

 anticipated by Professor Coin, who had been engaged in similar 

 researches and had come to much the same conclusions. Darwin 

 found that the bladders did not contain air, but water, or at most 

 a few casual bubbles. Consequently their final cause could not be 

 to float the plant. Crustaceans were commonly found by him in 

 mature bladders, and sometimes other minute creatures. Tlie 

 bladder, which was shaped like a flattened oval flask, only with the 

 lower edge straight, was a sort of trap, furnished with a very 

 delicate transparent valve at it.> mouth, and witli a few small 

 bristles, resembling the antennae of an insect, also about the mouth, 

 which seemed to be for the purpose of guiding crustaceans to the 

 entrance of tlie trap. The interior of the bladder is coated willi 

 elongate papillae, arranged in fours and in pairs, wliich are ca})able 

 of suction ; and Darwin succeeded in proving that the bladders 

 imbibed the juices of the decaying crustaceans, which were soon 

 asphyxiated by their confinement in the trap, and this ministered 

 to the nutriment of the plant. The Bladderworts (at least in this 

 country) have no root ; the bladders therefore carry on the 

 alimentary functions that roots perform in other plants, and feed 

 on microscopic garbage. It is noticeable that the British species 

 are inhabitants of remarkably foul ditches or putrid bogs. 



Utricularia vulgaris, L. Stems, 6-1 Sin. long, leafy throughout, 

 usually simple, terminating in stout winter buds ; leaves deltoid- 

 ovate in outline, spreading alternately in diftercnt directions, 

 sessile, trifurcate from the base, branching 3-1 times, segments 

 linear with fine marginal bristles towards the extremities, and 

 bearing bladders |l in. long shortly stalked ; scape erect at first, then 

 elongating procumbent and flexuous (G-Hin.), 3-12 flowered ; liracts 

 oblong olive green often bifid ; pedicels dotted erect in bud recurved 

 in fruit ; calyx pale olive green, half as long as the pedicel, lobes 



