Digestive System General, 59 



The Tongue attains in this class its full development as an 

 Organ of Taste {q.v.) : it is commonly divided into a free, 

 gustatory, and sensitive part ; but in the matter of freedom 

 we meet with every gradation, from almost fixity to high 

 extensibility. It subserves several different mechanical offices, 

 being instrumental in the prehension, distribution, and some- 

 times even trituration of food. 



Nearly all Mammalia have Salivary Gland^ ; the ratio of 

 their development varying directly with the nature of the 

 food and the time spent on mastication : they are larger in 

 those species which are Herbivorous than in those which are 

 Carnivorous, and are more highly developed in proportion as 

 the food is masticated for a longer period. The Glands com- 

 monly found pouring their secretion into the mouth are, the 

 Parotid, Submaxillary, and Sublingual: besides these there 

 are numerous Mucous Crypts* on the inside of the mouth and 

 on the Palate, e.g.^ Labial, Buccal, Zygomatic, Molar, and 

 Palatine. The Parotid, situated generally between the Ear 

 (irapa, near ; ovq, wt6q, the ear) and the lower Jaw, behind the 

 Masseter, penetrated by the Facial nerve, and whose duct 

 (ductus Stenonianus) opens between the Jaw and the Buccal 

 membrane in the neighbourhood of the upper Molar teeth, 

 is relatively the largest in Mammals that masticate most, 

 and feed chiefly on vegetables and fruit. The Submax- 

 illary, normally situated between or alongside the rami of 

 the lower Jaw, and whose duct (ductus Whartonianus) opens 

 inside the lower dental arch close to the fra3num of the Tongue, 

 upon the margin of the SubKngual, is largest in those species 

 that need the greatest amount of viscid lubricating secretion, 

 and have an animal or mixed diet. The Sublingual situated 

 by the side of the frsenum of the Tongue pours forth a viscid 

 secretion ; it is not always present. The Subsidiary Glands 

 are most developed in the Herbivorous Manimals in relation 



* Termed collectively the Subsidiary Glauds. 



