Chap. XVII.] STRUCTURE OF THE BLADDER. 327 



much shorter, and project at a smaller angle, that is, are 

 more nearly horizontal, and are directed towards the an- 

 terior end of the bladder. These arms are only moderately 

 sharp; they are composed of extremely thin transparent 

 membrane, so that they can be bent or doubled in any di- 

 rection without being broken. They are lined with a deli- 

 cate layer of protoplasm, as is likewise the short conical pro- 

 jection from which they arise. Each arm generally (but not 

 invariably) contains a minute, faintly brown particle, either 

 rounded or more conmionly elongated, which exhibits inces- 

 sant Brownian movements. These particles slowly change 

 their positions, and travel from one end to the other of the 

 arms, but are commonly found near their bases. They are 

 present in the quadrifids of young bladders, when only about 

 a third of their full size. They do not resemble ordinary 

 nuclei, but I believe that they are nuclei in a modified condi- 

 tion, for when absent, I could occasionally just distinguish 

 in their places a delicate halo of matter, including a darker 

 spot. Moreover, the quadrifids of Utricularia montana con- 

 tain rather larger and much more regularly spherical, but 

 otherwise similar, particles, which closely resemble the nu- 

 clei in the cells forming the walls of the bladders. In the 

 present case there were sometimes two, three, or even more, 

 nearly similar particles within a single arm; but, as we shall 

 hereafter see, the presence of more than one seemed always 

 to be connected with the absorption of decayed matter. 



The inner side of the collar (see the previous Fig, 20) is 

 covered with several crowded rows of processes, differing in 

 no important respect from the quadrifids, except in bearing 

 only two arms instead of four; they are, however, rather nar- 

 rower and more delicate. I shall call them the bifids. They 

 project into the bladder, and are directed towards its poste- 

 rior end. The quadrifid and bifid processes no doubt are 

 homologous with the papillse on the outside of the bladder 

 and of the leaves; and we shall see that they are developed 

 from closely similar papillte. 



The Uses of the several Parts. After the above long but 

 necfessary description of the parts, we will turn to their uses. 

 The bladders have been supposed by some authors to serve 

 as -floats-; but branches which bore no bladders, and others 

 from which they had been removed, floated perfectly, owing 



