CAENIVOROUS PLANTS 



133 



A few 



trivances which occur in plants of several different families, 

 of these I wish to discuss in some detail. 



The marshes of European countries, and also those of warmer lands, 

 often contain bladderworts, or Utricularise (Fig. 33) — floating water- 

 plants, without roots, and with horizontally spread, long-drawn-out, 

 tendril-like shoots, in part thickly covered with whorls of delicate, 

 needle-shaped leaves, in part bearing sparse leaves of quite peculiar 



Fig. 23. Utricularia graflana, after Kerner. A, a plant in its natural position, 

 floating in the water. FA, traps. B, a trap enlarged four times, ss, suctorial cells. 

 M, valve, which closes the entrance to the trap. C, suctorial cells on the internal wall 

 of the trap, enlarged 250 times. 



structure. These are stalked, hollow bladders (Fig. 33 A, FA), with 

 quite a narrow entrance at the apex, which is closed, as far as larger 

 animals are concerned, by projecting bristle-like hairs (B). Small 

 animals, such as water-fleas (Daphnia), species of Cyclops, and 

 Ostracods, can swim in between the bristles, and they then come 

 in contact with a valve which opens easily inwards [B, Id) and allows 

 them to penetrate into the interior of the trap. Once inside they are 



