GLANDS. 409 



When the follicles of a mammary gland in an active state 

 are examined, vast numbers of milk globules of various sizes 

 will be perceived within them ; and lying in the midst of 

 these, the small granular secreting cells will be seen : these, 

 however, do not contain milk-globules, from which it follows 

 that the milk corpuscles are not formed within the granular 

 cells, but external to them, although still within the cavity 

 of the follicles. (Plate lAV.figs. 3, 4, 5.) 



Mammary glands exist in the human male as well as 

 female breast, the essential structure being the same in both, 

 as proved by the many cases now on record, in which infants 

 have been suckled by men. 



In childhood and old age the mammary glands consist of 

 white fibrous tissue in the midst of which traces only of the 

 follicles can be perceived. 



Numerous lacteals arise from the neighbourhood of the fol- 

 licles ; by these, the more watery parts of the milk are absorbed 

 when this is retained for any length of time within the breast, 

 and in this way the distension of that organ is from time to 

 time relieved. 



LIVEK. 



The liver has been described as consisting, like the other 

 glands of the lobular form, of lobes, lobules, and follicles or 

 acini; and indeed in some of the lower animals, this organ has 

 such a constitution. It has, nevertheless, recently become a 

 matter of very great doubt whether in the Mammalia, at least, 

 the same type or organization prevails, and whether the struc- 

 ture of this gland in this class of animals is not of a totally 

 different kind. 



The mammalian liver consists indeed of lobes and lobules, 

 but the question is as to the existence of the follicles or acini 

 furnished with their efferent ducts. 



In the adult liver, the division into lobes, even, is essen- 

 tially arbitrary, so that, in fact, it is of lobules alone that the 

 liver is entirely composed. 



Lobules. The lobules of the liver are aggregations or 



