376 LECTURE XV. 



secreted into their interior, at first in small particles, 

 which soon become larger, and after a short time the 

 individual cells can no longer be distinctly perceived, 

 but only conglomerations of large drops, which rise up 

 out of the gland into the hair-follicle. If we unravel 

 the gland so as to form a flat surface, its layers of cells 

 would have the appearance of epidermis, only that the 

 oldest cells do not become horny, but are destroyed by 

 fatty metamorphosis. The secretion is a purely epi- 

 thelial one, like the seminal secretion. 



This process furnishes us at the same time with an 

 accurate representation of the formation of milk. You 

 need only imagine the ducts much lengthened, and the 

 terminal acini greatly developed ; the process remains 

 essentially the same : the cells multiply abundantly ; the 

 multiplied cells undergo fatty degeneration, and ulti- 

 mately there remains scarcely any material traces of 

 these cells excepting the drops of fat. The closest re- 

 semblance to the manner in which the secretion of seba- 

 ceous matter ordinarily takes place, is presented by the 

 earliest period of lactation when the so-called colostrum 

 is yielded. A colostrum-corpuscle (Fig. 112, C) is the 

 still coherent globule which results from the fatty de- 

 generation of an epithelial cell. The formation of colos- 



FIG. 112. 



Fig. 112 Mammary gland during lactation, and milk. A, Lobule of the mam 

 mary gland, with milk issuing out of it. B. Milk globules. C. Colostrum, a, a dis- 

 tinct fat-granule cell, 6, the same with evanescent nucleus. 280 diameters. 



