CH. XXVIII.] 



THE MAMMARY GLANDS. 



461 



Inmen containing a nucleus and the materials of the secretion, disintegrates 

 and goes to form the solid part of the milk. The cells also secrete water, 



Fig. 389. Dissection of the lower half of the female mamma, during the period of 

 lactation. I. In the left-hand side of the dissected part the glandular lobes are 

 exposed and partially unravelled ; and on the right-hand side, the srlandular substance 

 has been removed to show the reticular loculi of the connective-tissue in which 

 the glandular lobules are placed : i, upper part of the mamilla or nipple ; 2, areola ; 

 3, subcutaneous masses of fat; 4, reticular loculi of the connective-tissue which 

 support the glandular substance and contain the fatty masses ; 5, one of three lacti- 

 ferous ducts shown passing towards the mamilla where they open ; 6, one of the sinus 

 lactei or reservoirs ; 7, some of the glandular lobules which nave been unravelled ; 

 /, others massed together. (Luschka.) 



Fig. 390. Section of mammary gland of bitch, showing acini, lined with epithelial cells of 

 a short columnar form, x 200. (V. D. Harris.) 



silt-, and milk sugar. The fat, &c., of milk are not simply picked out from 

 the blood by the secreting cells, but these materials are formed by metabolic 



],:, within the protoplasm of the cells. 



