TEGUMENTARY ORGANS 



419 



a very slight and local, but in Batrachia and Mammalia, an immense 

 development. In the frog, the whole surface of the ecderon is beset 

 with minute trifid apertures, so disposed between three epidermic 

 cells, as to present a singular resemblance to the stomata of plants 

 {fig- 318- b). These lead directly into spherical sacs {fig. 318. A. d^^ 

 which are lined by a continuation of the cellular ecderon, and lie in 

 the superficial part of the enderon above 

 its stratified layer {fig. 318. A. g?) {vide 

 infra). Nerves (/) and vessels pene- 

 trate the latter to reach the superficial 

 layer of the enderon, and ramify among 

 these close-set glandular sacs. The sacs 

 usually contain only a clear fluid ^ ; they 

 are contractile, and may be made to 

 expel their contents by irritation of the 

 nerves distributed to them.^ 



In Mammals, we meet with two 

 kinds of cutaneous glands, sebaceous 

 and sudoriparous. The former are almost 

 invariably developed in connection with 

 the hair sacs, consisting in fact of 

 diverticula of the Malpighian layer of 

 the cellular ecderon of the upper por- 

 tion of these sacs, whence their position 

 is always superficial. The innermost 

 cells of the solid process become filled 

 with fat — break down, and pour their 

 contents into the hair sac itself, by whose 

 aperture they make their exit. Sometimes, as in the hairs of the 

 head in man and in the pig's bristles, the sebaceous glands are 

 very small and simple, while in other localities they throw out pro- 

 cesses, and assume the appearance of complex racemose gland.s 

 disposed like rosettes around the hair-sac, from which they are 

 developed. 



Sudoriparous glands. — These glands, like those just described, are, 

 as Gurlt pointed out, simple, elongated processes of the deep layer of 

 the ecderon, differing from the sebaceous glands chiefly in producing 

 a clear fluid, instead of a fatty secretion. As Kolliker has shown,. 

 however, no line of demarcation is to be drawn on this ground, the 



'• Stated by Bergmann and Leuckart to have an irritating property in Triton. 

 2 Ascherson : Haut-drlisen d. Frosche, Mii'Uer's Archiv. 1841. Czermak : Haut-nerven 

 d. Frosche. Ibid. 1S49. 



E E 2 



Fig. 318. — The cutaneous glands of 

 the Frog. A, section ; B, super- 

 ficial view. 



