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Show 402 UTRICULARIA NEGLECTA. CHAP. XVII. tween the inner and outer surface consists of coarse cellular tissue (:fig. 20). The inner side is thickly covered with delicate bifid processes, hereafter to be described. The collar is thus made thick; and it is rigid, so that it retains the same _outline whethei~ 1t~e bladder contains little or much air and water. Ihis is of great importance, a~ otherwise t~e thin and flexible valve would be liable to be distorted, and in this case would not act properly. Altogether the entran~e i~to the blad~er, forme~ by the transparent valve, with It~ four obliquely proJecting bristles, its numerous d1vers_ely shaped glands, surrounded by the collar, be~nng glands ?n the inside and bristles on the outside, together w1th the bristles borne by the an tennm, presen ~s an extraordinarily complex appearance when VIewed under the microscope. We will now consider the internal structure of the bladder. The whole inner surface, with the exception of the valve, is seen under a mod era tel y high power to be covered with a serried mass of processes (fig. 21). Each of these consists of four divergent arms; whence their name of q uadri:fid processes. They arise from small angular cells, at the junctions ?f th.e angles of the larger cells which form the 1ntenor of the bladder. The middle part of the upper surface of. these small cells projects a little, and then contracts Into a very short and narrow footstalk which bears the four arms (fig. 22). Of these, two are lo~g, but _often of not quite equal length, and project obliquely 1nw~rds and towards the posterior end of the bladder. rhe two others are much shorter, and project at a smaller angle, that is are more nearly horizontal, and are directed towards' the anterior end of the bladd e r. The se ar·m s are only moderately sharp; they are composed of ex- CHAP. XVII. STRUCTURE OF THE BLADDER. 403 tremely thin transpar~nt membrane, so that they can be bent or doubled_ In a~y direction without being broken. They are hued WIth a delicate layer of . t _ I . l'k . pro o p asm, as Is I ewise the short conical projection from whi.ch they ari~e. Each arm generally (but not inv~ nably) contains a minute, faintly brown particle, either rounded or more commonly elongated wh' h h'b' . , IC ex I Its Incessant Brownian movements. These par- FIG. 21. ( Utricularia neglecta.) Small portion of inside of bladder, much enlarged, showing quadl'ifid processes. FIG. 22. ( Ct1·icula1·ia neglecta.) One of the quadrifid processes greatly enlarged. ticles sl<?w l y change their positions, and travel from one end to th~ other of the arms, but are commonly f?und near their bases. They are present in the quad. rrfi~s of y~ung bladders, when only about a third of then full ~Ize. They do not resemble ordinary nuclei, but I beheve that they are nuclei in a modified con~ itio~, for. when. absent, I could occasionally just distinguish In their places a delicate halo of matter incl~ding. a darker spot. Moreover, the quadri:fids of Utru;ular~a 1nontana contain rather larger and much 2 D 2 |
