Die, KM l<>\ 



'37 



whic li i^ discharged along its duct. This process is called 

 secretion. 



When the cubical cells of glands arc examined microscopic- 

 ally they are found to usually contain, in addition to a nucleus, 

 many granules, sometimes fine, sometimes coarse, as we saw 

 was often the case with the white corpuscles of the blood. The 

 granules of material in the cells are made by the living cell sub- 

 stance itself ; and when the cells are secreting, water and other 

 substances pass through the cells from the capillaries around 

 them, while at the same time the cells discharge these 

 granules of material, which 

 dissolve in the water and are 

 carried away in solution along 

 the duct. Secretion is not 

 merely due to filtration or 

 exudation from the blood- 

 vessels, but is brought about 

 by the agency of the gland 

 cells, the function of which is 

 to draw certain substances 

 from the blood, and to add to 

 these more or less material of 

 their own manufacture. 



The glands of the mucous 

 membrane of the mouth se- 

 crete a small amount of fluid 

 which is discharged into the 

 mouth, but the saliva is 

 secreted by special glands 

 called the salivary glands. 



The Salivary Glands. 

 The salivary glands arc large racemose glands, situated 

 at some little distance from the cavity of the mouth, the ducts 

 leading from each gland to the mouth being about two inches 

 long. There are three pairs of salivary glands : one placed in 

 front of each car, called the parotid glands ; one under the 

 lower jaw on each side, called the submaxillary glands ; and a 

 pair situated under the tongue, called the sublingual glands. 



Plai ing fund in tin- mouth, or even the sight or smell of 

 fund, will cause a (low of saliva into the mouth. This is brought 



Fi 



I 



61. Dissection to show the salivary 



glands. 



The sublingual gland, ami A. the sub- 

 maxillary, with their ducts o|>enini; 

 into the floor of the mouth liy the 

 tongue at </; c, parotid gland with duu 

 opening into the mouth at e. 



