408 THE SOLIDS. 



Such is a brief description of the salivary glands in their 

 adult form : in their embryonic condition, however, they do 

 not consist of lobes and lobules, but the terminal efferent 

 ducts end in single follicles, which afterwards become mul- 

 tiplied, until at length clusters of them appear, the incipient 

 lobules. (Plate lAV.figs. 1, 2.) 



The structure of these glands may be readily followed out 

 without the aid of injection.* 



LACHRYMAL GLANDS. 



These glands resemble the salivary in all essential structural 

 particulars : they are, however, separated from them in con- 

 sequence of the difference in the character of the secretion 

 which they furnish. 



MAMMARY GLANDS. 



The mammary glands do not require any lengthened de- 

 scription, since they also are formed upon precisely the same 

 type as the salivary and lachrymal glands. 



The principal structural difference has reference to the ef- 

 ferent ducts. Each salivary gland is furnished with but a 

 single excretory duct, while to each mammary gland there 

 are as many as eight or ten ducts which open on the apex of 

 the nipple : the ducts of the mammary gland are also re- 

 markable for their great capacity, for it is in them that the 

 milk principally collects when it is allowed to accumulate. 



* It will be observed, that the above description of the salivary 

 glands agrees closely with that ordinarily given. An examination of these 

 glands instituted since this description was in type, has convinced me 

 that they approach in organization very nearly to the mucous glands of 

 which they are to be considered as a variety. The salivary glands differ 

 indeed from the mucous in the particulars already mentioned, viz. in the 

 less size of the follicles, and in their more complete shape, but neverthe- 

 less are formed upon a similar type of organization. The efferent duct 

 with which each of the follicles of the salivary glands is said to be fur- 

 nished is so short, that it in very many instances scarcely deserves the 

 name of such ; the general arrangement is that of a number of follicles 

 almost sessile, clustering around the terminations of the salivary ducts. 



