818 



THE SALIVARY GLANDS. 



between it and the submaxillary gland ; but it is here in close contact 

 with the Whartonian duct, with the accompanying deep portion of the 

 last-named gland, and also with the lingual nerve. 



The lobules of the sublingual gland are not so closely united together 

 as those of the other salivary glands, and the ducts from many of them 

 open separately into the mouth, along the ridge which indicates the posi- 



Fig. 574. 



B. 



Fig. 574. SKETCHES ILLUSTRATING THE FORMATION OF THE PAROTID GLAND (from 



J. Muller). 



A, head of a foetal sheep magnified, showing the early simple condition of the parotid 

 gland with the duct injected. 



B, parotid gland of a foetal sheep more advanced, the ducts and blood-vessels injected. 



tion of the gland. These ducts, named ducts of Jtivitii, are from eight to 

 twenty in number. Some of them open into the duct of Wharton. One, 

 longer than the rest (which is occasionally derived in part also from the 

 submaxillary gland), runs along the Whartonian duct, and opens either 

 with it or very near it ; this has been named the duct of Bartholin. 



The blood-vessels of this gland are supplied by the sublingual and submental 

 arteries and veins. The nerves are numerous, and are derived from the lingual 

 branch of the fifth pair. 



Saliva. The saliva is a clear limpid fluid, containing a few microscopic 

 granular corpuscles. Its specific gravity is from 1 '006 to 1 '008, and it has 

 only from 1 to 1-| parts of solid matter in 100. The saliva is always alkaline 

 during the act of mastication ; but the fluid of the mouth becomes acid, and 

 remains so until the next time of taking food : the reason being that the 

 secretion of the mucous follicles of the mouth is acid, while that of the 

 salivary glands is alkaline. Its chief ingredients, besides water and mucus, 

 are a peculiar animal extractive substance, named salivine, with some 

 alkaline and earthy salts. It is remarkable, besides, for containing a minute 

 proportion of sulphocyanide of potassium. 



