General principles of zoology . FIG. 54. FIG. 55. FIG. 54.—Longitudinal section through the nutritive polyp of a Siphonophore. (AfterHaeckel.) O, mouth-opening j en, entoderm ; ek, ectoderm. FIG. 55.—Stenostoma leucops, in division, a, ectodermal fore-gut, at a forming anew for thehinder animal; >«, the blindly ending entodermal mid-gut ; e, ectodermal ciliated epithe-lium ; f, ganglion with ciliated pit ; iv, water-vascular canal; g, ganglion of the hinderanimal. * As a substitute for the somewhat cumbrous terms digestivetract, alimentary canal, etc., the term g ut is coming into use among
General principles of zoology . FIG. 54. FIG. 55. FIG. 54.—Longitudinal section through the nutritive polyp of a Siphonophore. (AfterHaeckel.) O, mouth-opening j en, entoderm ; ek, ectoderm. FIG. 55.—Stenostoma leucops, in division, a, ectodermal fore-gut, at a forming anew for thehinder animal; >«, the blindly ending entodermal mid-gut ; e, ectodermal ciliated epithe-lium ; f, ganglion with ciliated pit ; iv, water-vascular canal; g, ganglion of the hinderanimal. * As a substitute for the somewhat cumbrous terms digestivetract, alimentary canal, etc., the term g ut is coming into use amongbiologists to designate the canal as a whole. GENERAL CA GA.\OLOGY. 12 5 important for the well-being of the animal, it is to be ex-pected that of all the organs in the animal series the diges-tive tract should be formed first, and also in almost every•case should be earliest established in the embryo. Thefact that many worms (Cestodes) and crabs (Rhizocepliala]have no digestive tract does not alter this statement; forwi
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1896
