suct. 210.] DEVELOPMENT OF THE MAMMM. 473 



arc never so for developed as in the female ; they cither correspond 

 in form to the ducts which are met with in the glands of newly- 

 born infants, or they will be found in larger specimens of the male 

 gland, to be variously ramified and beset with a certain number of 

 terminal vesicles, which, on account of their considerable size, 

 cannot be regarded as true gland-vesicles or acini. Indeed, ac- 

 cording to hanger, their size is three times greater than that of 

 the true gland-vesicles in the female, but Luschka describes them 

 as only 0-02'" in width. In rare, but well established cases, the 

 male gland may take on such a development, that it becomes fit 

 lor the secretion of milk. 



§ 210. Physiological Remarks.— The development of the mam- 

 mary gland follows the same course as the other superficial glands, 

 and, at its first appearance, in the fourth or fifth month, consists 

 of nothing but a solid, papilliform process of the mucous layer of 

 the epidermis, which is enveloped by a layer of dense cuticular 

 tissue (see my researches in Mitth. d. Zurcher nat. Ges., 1850, 

 No. 41). Then, by sending out a certain number of processes, the 

 first rudiments of the subsequent lobes arise in the sixth or seventh 

 month. At their origin, the lobes are nothing but small, pyri- 

 form, or flask-shaped processes, proceeding from the common 

 gland-rudiment; but towards the end of foetal life, these become 

 isolated from each other, and open externally, while, at the same 

 time, they are beginning to give off roundish or elongated solid 

 processes at their closed extremities. At the period of birth the 

 gland measures i| to 4 lines, and exhibits distinctly a certain 

 number of segments, twelve to fifteen in number, the inner of 

 winch approach to the still rudimentary nipple, and there ter- 

 minate, either by a simple flask-shaped neck, or with two or three 

 dilatations j while the outer segments are connected with a greater 

 number of such dilatations. The excretory duct of each of these 

 rudimentary lobules, which is either simple or branched two or 

 three times, is composed of a fibrous coat of immature, nucleated 

 connective tissue, with a small cylindrical epithelium. The ducts 

 are distinctly hollow, while their bulbous ends are still destitute 

 of a cavity, and can no more in this, than in other developing 

 glands, be called terminal vesicles, seeing that they consist of 

 nothing more than small nucleated cells, with the fibrous envelope 

 which passes over them from the ducts. From this verv simple 

 form, the subsequent structure is developed by the continual form- 

 ation of processes from the primitive and subsequently formed 



