. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. INTEGUMENT 19 layer is composed of more cylindrical or cubical cells. The former corresponds to the stratum corneum, the latter to the stratum Malpighii. The horny layer is shed periodically, either entire or in pieces. Later, with advancing development, the layers of the epidermis become more numerous, and involutions towards the dermis take place in all parts, giving rise to a great number of sac-like and tube-shaped glands similar to those of Protopterus (p. 17); these are particularly abundant in certain regions—mo
. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. INTEGUMENT 19 layer is composed of more cylindrical or cubical cells. The former corresponds to the stratum corneum, the latter to the stratum Malpighii. The horny layer is shed periodically, either entire or in pieces. Later, with advancing development, the layers of the epidermis become more numerous, and involutions towards the dermis take place in all parts, giving rise to a great number of sac-like and tube-shaped glands similar to those of Protopterus (p. 17); these are particularly abundant in certain regions—more especially on the head and flanks (Fig. 12). The individual glands are sur-. '^Tm Fig. 12.—Section through the Skix of Adult Sala:maxder (S. maculosa Ep, epidermis ; Go, dermis, in the richly pigmented (Pi) connective-tissue stroma of which tlie various sized integumentary glands (A, O, D, D, E) lie embedded ; 3P, the muscular layer of the glands, lying within the basement membrane (Pr) ; M, the same, seen from the surface ; E, epithelium of glands ; .S', secretion of glands ; Mm, subcutaneous layer of muscles, through which vessels ((?) extend towards the dermis. rounded by muscle and connective-tissue fibres, pigment, blood- vessels, and nerves. Their secretion serves to keep the skin moist, but as experiments have shown, it also forms an important weapon of defence on account of its poisonous properties. This richness in glands is a characteristic of the skin of Amphi- bia and to it they owe their moist and slippery nature. Frequently, as for instance in Toads, the skin is not smooth, but has a rough, warty appearance, caused by local proliferations of the epidermis. Epidermic claws, analogous to those of the Amniota, are present only in Xenopus (Dactylethra) and Onychodactylus. The pigment, accumulated principally in the dermis—partly diffused, partly enclosed within the cells—is under the control of the nervous system, and thus renders a change of colour possibl
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
