THE TONGrE. 195 



low. The fourth appears about the expiration of the eightli month, 

 and the fifth at the end of the year, about which ""ime the first mo- 

 lar is shed. The second is disphiced at the end of the second year, 

 and so with the rest, at intervals of a year ; but the sixth molar, 

 which is from the beginning a permanent tooth, does not appear un- 

 til the sixth year. 



THE TONGUE. 



The tongue occupies the base of the mouth. It is firmly held by 

 muscles principally attached to the os hyoides, a singular bone common 

 to it and the larynx. The tongue is composed of the union of these 

 muscles, which extend their fibres through every part of it, and with 

 which is intermingled a considerable quantity of fatty matter. It is 

 covered by the membrane of the mouth, but curiously modified ; 

 it resembles more the cuticle or scarf-skin, but the internal layer is 

 fibrous and sensitive, and between the two is a soft, reticulated sub- 

 stance, which serves as a bed for the papillae, or little eminences 

 scattered all over the tongue, some of which, at least, are supposed 

 to be the terminations of the gustatory nerve, or that branch of the 

 fifth pair of nerves on which the sense of taste depends. The use 

 of the tongue, generally, is to dispose of the food between the 

 grinders during mastication ; to collect it afterwards, and, by the as- 

 sistance of the bars, form it into a pellet for swallowing ; it is also 

 the main instrument in drinking. The outer covering of the tongue 

 of the ox is hard and rough. The peculiar way in which the food 

 is gathered renders this necessary ; it helps to collect the grass to- 

 gether and form it into a roll before it is brought between the pad 

 of the upper jaw and the incisor teeth of the lower one ; it serves 

 to clean the muzzle from annoyances to which it is exposed by means 

 of dirt or insects ; and it likewise wipes from the nostril the filth 

 that is discharged from it in various diseases of the membrane of the 

 nose or the air passages, to which the ox is so subject. 



The reader will remark the spur projecting from the centre of the 

 body of this bone, /^. 1. In some animals it is from two to three 

 inches in extent, and penetrates deeply into the root and body of the 

 tongue ; and from its sides, roughened for the purpose, there spring, 

 through the whole extent of the bone, powerful muscles (the genio- 

 hyo-glossi muscles, belonging to the chin, the hyoid bone, and the 

 tongue), whose object is to draw down the tongue within the mouth, 

 and limit its action. 



There is nothing about the ox which requires confinement of the 

 tongue ; but, on the contrary, he has need of one possessing an ex- 

 traordinary freedom of motion, and the os hyoides is small. Its 

 spur (1. p. 196) is a mere tubercle. There is no penetration or con- 

 finement of the root of the tongue. The muscles springing from it 



