The Mammary Glands arise in essentially the same manner as the other glands of the skin[151]. The glands of each side are formed as a solid bud of the mucous layer of the epidermis. From this bud processes sprout out, each of which gives rise to one of the numerous glands of which the whole organ is formed. Two very distinct types in the relation of the ducts of the glands to the nipple are found (Gegenbaur, No. [313]).
Bibliography of Epidermis.
General.
(304) T. H. Huxley. “Tegumentary organs.” Todd’s Cyclopædia of Anat. and Physiol.
(305) P. Z. Unna. “Histol. u. Entwick. d. Oberhaut.” Archiv f. mikr. Anat. Vol. XV. 1876. Vide also Kölliker (No. [298]).
Scales of the Pisces.
(306) O. Hertwig. “Ueber Bau u. Entwicklung d. Placoidschuppen u. d. Zähne d. Selachier.” Jenaische Zeitschrift, Vol. VIII. 1874.
(307) O. Hertwig. “Ueber d. Hautskelet d. Fische.” Morphol. Jahrbuch, Vol. II. 1876. (Siluroiden u. Acipenseridæ.)
(308) O. Hertwig. “Ueber d. Hautskelet d. Fische (Lepidosteus u. Polypterus).” Morph. Jahrbuch, Vol. V. 1879.
Feathers.
(309) Th. Studer. Die Entwick. d. Federn. Inaug. Diss. Bern, 1873.
(310) Th. Studer. “Beiträge z. Entwick. d. Feder.” Zeit. f. wiss. Zool., Vol. XXX. 1878.
Sweat-glands.
(311) M. S. Ranvier. “Sur la structure des glandes sudoripares.” Comptes Rendus, Dec. 29, 1879.