136 



MANUAL OF PHYSIOLOGY. 



sack, their outer side following accurately the concave boundary 

 of the saccule, their inner side impinging upon the gland cells. 

 They thus acquire a more or less half-moon shape. These demi- 

 lune cells will be again referred to (page 146). 



Between the saccules are numerous blood vessels which branch 

 and form a network of capillaries on the outside of each little sack. 

 Numerous nerves are also found, which, according to some 

 observers, have ganglionic cell connections in the gland sub- 

 stance, and send terminals into the gland cells direct. 



Although this account of the nerve terminations in the secreting 

 cells of other glands has met with doubt, it is certain that in the 



FIG. 62. 



A dissection of the side of the face, showing the Salivary Glands. a. Sublingual gland . 

 b. Sub-maxillary glands with their ducts opening on the floor of the mouth beneath the 

 tongue at d. c. Parotid gland and its duct, which opens on the inner side of the cheek. 



lower animals nerve terminals have been traced into gland cells, 

 and upon physiological grounds, as will presently appear, we are 

 forced to believe that a similar connection must exist in mam- 

 malia. 



The ducts are lined with ordinary cylindrical epithelium which 

 does not appear to have any secreting function. All the glands 

 are made up of numerous packets of lobules bound together in 

 one mass. Each of these lobules is itself a perfect gland, so that 

 even the smaller mouth glands are separable into lobules, and 

 hence are called compound acinous glands. 



