SALIVA IN THE DOG. 171 



general. In it, as in man, the resemblance to a spur fails. It 

 is connected, as in these, by muscular fibres with the lower 

 jaw, the temporal bone, the larynx, the pharynx, and the 

 breast bone, and is concerned in particular with the act of 

 deglutition. 



The tongue, besides being the organ of taste, to which the 

 papillae on its surface are subservient, is of important use, as 

 already stated when speaking of the mouth of the horse, in 

 the mastication of the food, and in the act of swallowing (p. 20). 



Salivary Glands. The salivary glands are not so largely 

 developed in the dog as in the horse and in ruminant animals. 

 The glands, however, bear the same names, and occupy cor- 

 responding situations. The parotid gland in the dog is of a 

 crescentic form, embraces the concha of the ear, and extends as 

 far as the submaxillary gland, which equals it in size. The 

 sublingual gland seems to be little more than a prolongation of 

 the submaxillary gland, or, according to Cuvier, the sublingual 

 gland is wanting in the dog, and what has been taken for it 

 is a small gland accessory to the submaxillary lying along 

 Wharton's duct. The situation of these glands, as well as their 

 general structure, will be understood by what has been said of 

 the corresponding organs in the horse (p. 21). 



Ordinary saliva is a mixture of the secretion of the buccal 

 mucous membrane and of the several glands. The parotid secre- 

 tion in the dog is limpid and colourless, devoid of smell and 

 taste, incapable of being drawn out into threads, and of a dis- 

 tinctly alkaline reaction. Its specific gravity varies from 

 1.0040 to 1.0047. The same secretion contains, of inorganic 

 matters, alkaline chlorides, carbonate of lime, carbonate of 

 potassa, phosphate of lime and magnesia, phosphate of soda, 

 and sulphate of soda. Among the organic matters are ptyalin, 

 alcohol extract, and sulphocyanide of potassa. 



The secretion of the submaxillary glands of dogs is like that 



