238 



ELEMENTARY PHYSIOLOGY 



LESS. 



The submaxillary and sublingual glands lie between the 

 lower jaw and the floor of the mouth, the submaxilliry 

 being situated further back than the sublingual. Their 

 ducts open in the floor of the mouth below the tip of the 

 tongue. The secretion of these salivary glands, mixed 

 with that of the small glands of the mouth, constitutes 

 the saliva. 



The salivary glands are built up on the type shown in 

 Fig. 68, 6. The essential part of the structure lies in the 







■-AU'li 



a 



Fio. 73. — Sections of the Submaxillary Gland. 



A, at rest ; B, after secretory activity. 



a, a, demilune cells. 



cells which line the dilated ends, or alveoli, of the finest 

 branches of their ducts. In a section of a submaxillary 

 gland which is resting, that is, has not been secreting for 

 some time, the cells are large and nearly fill the alveoli. 

 Each cell has a nucleus j)laced near its outer end and 

 surrounded by a small amount of protoplasm which is 

 granular and stains readily. The (larger) rest of the cell 

 is quite clear an,d transpai'ent and stains with great diffi- 

 culty if at all (Fig. 73, A). Since the material compos- 



