CHAP.XVn.] STRUCTURE OF THE BLADDER. 323 



axis or stem; but the footstalks must have some power of 

 movement; for in plants kept in my greenhouse the ventral 

 surface was generally turned either straight or obliquely 

 downward. The Rev. H. M. Wilkinson examined plants for 

 me in a state of nature, and found this commonly to be the 

 case, but the younger bladders often had their valves turned 

 upwards. 



The general appearance of a bladder viewed laterally, with 

 the appendages on the near side alone represented, is shown 

 on the opposite page (Fig. 18). The lower side, where 

 the footstalk arises, is nearly straight, and I have called it 

 the ventral surface. The outer or dorsal surface is convex, 

 and terminates in two long prolongations, formed of several 

 rows of cells, containing chlorophyll, and bearing, chiefly on 



Fig. 19. 



(Utrieularia negleeia.) 



Valve of bladder ; greatly enlarged. 



the outside, six or seven long, pointed, multicellular bristles. 

 These prolongations of the bladder may be conveniently 

 called the antennce, for the whole bladder (see Fig. 17) 

 curiously resembles an entomostracan crustacean, the short 

 footstalk representing the tail. In Fig. 18, the near antenna 

 alone is shown. Beneath the two antennte the end of the 

 bladder is slightly truncated, and here is situated the most 

 imjwrtant part of the whole structure, namely the entrance 

 and valve. On each side of the entrance from three to rarely 

 seven long, multicellular bristles project outwards ; but only 

 those (four in number) on the near side are shown in the 

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