THE SALIVA. 



189 



structure, their substance being composed of dis- 

 tinct irregularly spherical or ovoidal masses, 

 more or less flattened into a polygonal form by 

 mutual compression. The separate divisions or 

 lobules are connected with corresponding ter- 

 minal branches of the salivary duct, which pene- 

 trate into their interior, and there divide into 

 smaller tubes each one of which finally termi- 

 nates in a rounded sac called the glandular 

 follicle or alveolus. The appearance presented 

 upon an injection of such a lobule is as if the 

 follicles were arranged in clusters, like grapes, 

 around the ends of the smaller salivary tubes. 

 (Fig. 34.) A more complete examination has 

 shown, however, that the follicles are simply 



the rounded extremities of tubular or sac-like offshoots from the 

 salivary tube ; and that it is the windings and prolongations of the 

 tube itself which constitutes the secreting follicles of the gland. The 

 follicles themselves are in general about 50 mmm. in diameter, and 

 are lined with the glandular epithelium cells, which cover their in- 

 ternal surface and nearly fill their cavity ; so that there is frequently 

 to be seen only a comparatively small space toward the central part 

 of the follicle, containing a transparent fluid, produced by the secreting 



Fig. 35. 



LOBUI.B OF PAROTID 

 GLAND of newly-born in- 

 fant, injected with mercury. 

 (Wagner.) 



Two SALIVARY TUBES FROM THE LOBULE OF A MTTCIPAROUS GLAND, entering 

 the main duct. a. Duct of the lobule, b. Salivary tube, c. Follicles, on one Bide, as they 

 appear in situ. d. Follicles separated from each other, showing the windings and offshoots 

 of the salivary tube. (Kulliker.) 



action of the cells. The glandular cells, which are arranged in a 

 single layer, are finely granular bodies, about 15 mmm. in diameter., 

 each one provided with an oval nucleus, situated toward the external 

 part of the follicle. The cells are closely packed together, and are of 

 various polygonal forms. 



The salivary tubes or ducts, outside the follicles, unite into larger and 

 larger branches, until they reach the principal excretory duct of the gland. 

 They are lined with a layer of cells which vary in form from those of 

 the follicles, being elongated and cylindrical, and provided with a nucleus 

 which is situated about their middle portion. It is very probable that 

 the epithelium of the salivary ducts, as well as that of the follicles, takes 



