. The Cambridge natural history. Zoology. TADPOLES 57 will-chaui1)er and the finny margins of the tail; l)ut the change t'loni the tadpole U) the final Anurous animal implies an almost entire reorganisation. In the earliest condition the embryo consists of a. large head and body, while the tail is still absent. Behind the beginnings of the future mouth appears a transverse crescentic fold, with the convexity looking backwards, which develops into tiie paired or unpaired adliesioc /q)2) This consists of large complex glands, developed in the Malpighian layer, originally covered hj the
. The Cambridge natural history. Zoology. TADPOLES 57 will-chaui1)er and the finny margins of the tail; l)ut the change t'loni the tadpole U) the final Anurous animal implies an almost entire reorganisation. In the earliest condition the embryo consists of a. large head and body, while the tail is still absent. Behind the beginnings of the future mouth appears a transverse crescentic fold, with the convexity looking backwards, which develops into tiie paired or unpaired adliesioc /q)2) This consists of large complex glands, developed in the Malpighian layer, originally covered hj the cuticida, which soon disappears, whereupon tlie sticky secre- ti<^n enables the larA'a to attach itself to the gelatinous mantle of the egg, later on to weeds or other objects in the water. The name of suckers, often applied to this apparatus, conveys a wrong. â Fi(i. 9. â Four stages of the development of the apparatus (.1) of Bufo rulyaris .⢠.1/, Mouth ; S2}.T. spiracular tube. lu 3 the gills are almost completely hidden V)y the united right and left opercular folds. The small outlined figures indicate the shape and natural size of the tadi)oles. (After Thiele.) idea, there being neither muscles nor any suctorial functi(jn. The shape of this organ undergoes many changes during the early life of the individual, and differs much in the various genera, affording thereby diagnostic cliaracters.^ At first a crescent, it divides into a right and a left oval or disc, whicli either remain asunder and behind the mouth {liana, Bufo), or they move for- wards to the corners of the mouth {Hyla^ or further back, and unite again more or less completely, as in Plscojilossus and B()) It is mostly of short duration, and disappears l)y the time that the larva, by the proper development of the gills and the tail and the functional mouth, changes into the tadpole. l)ut in a few s])ecies these discs transform themselves into an elaborate ventral disc. Such an org
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
