II Pitcher Plants 31 



paring the form in question with that of nearly related 

 plants ; partly by observation of the young plants and their 

 gradual development ; partly by attention to those mon- 

 strosities which often reveal the secret of strange structures. 

 It is only when the student has learned to place himself at 

 the standpoint of several distinct theories, and to state and 

 weigh these impartially, that he becomes able to give his 

 adherence to one or other view. Nor can he fully do 

 this without reading for himself the original papers, and 

 perhaps reinvestigating the subject for himself after all. 



Bladderwort. Our tour round the world in search of 

 pitcher-plants may find appropriate completion in the dis- 

 covery of one not less interesting almost at our own doors. 

 In marshy lochs and mountain tarns the Common Bladder- 

 wort makes itself conspicuous for a month or two in 

 summer, when from the floating stem the flower-stalk rises 

 bearing quaint bright golden blossoms, somewhat orchid- 

 like in appearance, though really akin to the primroses, 

 which are commonly considered to represent the simpler 

 regular ancestral form, much as do lilies to orchids, or potato- 

 blossom to foxgloves and snapdragon. At other times the 

 plant is not so readily seen, for it floats in the water, and 

 its leaves are small. Like some other aquatic plants the 

 water bladderworts have no roots, and the straggling stem 

 bears numerous, much-divided slender leaves. Among 

 these are hundreds of little bladders. From the main 

 submerged stem of Utricularia vulgarts, and yet more 

 markedly in tropical species, peculiar thin shoots, which 

 Gcebel calls "aerial shoots," rise to the surface, and bear 

 leaves slightly different from those on the other parts of 

 the stem. It seems likely that this part of the plant is 

 of special use in effecting interchange of gases with the 

 air. 



Each bladder shown by its mode of development to be 



