230 



HEALTH AND DISEASE 



In the male there are 40, namely 12 incisors, 4 canines, and 24 molars, 

 which are thus arranged in the upper and lower jaw: — 

 i. c. M. 



3_3 1_1 6 G 



3 3 11 6 6 



The mare is not provided with canine teeth or tusks. The teeth are 

 composed of three substances of different degrees of hardness, the softest 

 being named cement, the next harder dentine, and the hardest of all enamel. 

 These wearing away with different degrees of rapidity, leave on the grinding 

 surface ridges and sharp edges admirably adapted for the purpose they 

 have to fulfil, of reducing the food, with the aid of the saliva, to a pulp. 



Salivary glands (figs. 76, 77). — There are three chief pairs of sali- 

 vary glands, which have received the names of parotid, submaxillary, and 



Jugular vein. 8 Submaxillary 



Lal.ial .lut-ls. 



sublingual, together with several subordinate glands known as the molar, 

 or buccal, labial. Inajuaf, and stapJii/liuc. They have a united weight of 

 about 8000 grains avoirdupois, or about l£ lbs. The parotid gland is by 

 far the largest of the three principal pairs, weighing as much as four times 

 the two others put together. The sublinguals are the smallest. The 

 position of the several glands is shown in the adjoining wood-cuts. 



In external appearance the salivary glands are of yellowish -white 

 colour, and are easily broken up into small granules named lobules. In 

 their structure they present a remote resemblance to a bunch of grapes 

 (fig. 78), and have hence been termed racemose glands, the stalks of the 



