Elementary text-book of zoology, tr Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote elementarytextbo01clau Year: 1892-1893 CUTANEOUS 77 tubule, into which projects a coil of arterial blood vessels known as the gloinerulus (fig. 72). Very generally the outer body surface is the seat of special secre- tions which frequently play an impor- tant part in the economy of the animal, and are used especially as a means of protection and defence. The same is true also of the secretions of the accessory glands opening into the anterior or po
Elementary text-book of zoology, tr Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote elementarytextbo01clau Year: 1892-1893 CUTANEOUS 77 tubule, into which projects a coil of arterial blood vessels known as the gloinerulus (fig. 72). Very generally the outer body surface is the seat of special secre- tions which frequently play an impor- tant part in the economy of the animal, and are used especially as a means of protection and defence. The same is true also of the secretions of the accessory glands opening into the anterior or posterior end of the ali- mentary canal (salivary glands, poison glands, anal glands) (fig. 73). To the class of cutaneous glands belong, in the first place, the sweat- glands and the sebaceous glands of Mammalia. The fluid secretion of the former, on account of the ease with which it is evaporated, is of special use in keeping the body cool, while that of the latter keeps the integument and FIG. 71.—Diagrammatic represen- tation of the kidney (segmental organs) of a dog-fish embryo (after C. Semper). Wtr, ciliated funnels; Ug, kidney duct. 7>
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