ti DIGESTION AND FOOD. 



Kestricting our observations to the domestic animals, W3 

 find the prehension of food is effected by different organs. 



In the dog and cat, the fore-limbs indicate to a certain 

 extent the power which is given to man to grasp food and 

 carry it to the mouth. The stout and solid limbs of herbivo- 

 rous quadrupeds are, however, alone destined for support and 

 progression, and a long neck, and peculiarly shaped head, 

 favour the prehensile organs, whether they be lips, jaws, teeth, 

 or tongue. 



The organs of prehension are chiefly composed of muscular 

 tissue, amongst which, fat and glandular structure are inter- 

 spersed, and the whole covered by integument or mucous 

 membrane. Both tongue and lips are thus provided with 

 active moving power; and, we notice, in the lips of the horse 

 in particular, a well-developed orbicular, or circular muscle, 

 composed of fibres, which form a complete ring within 

 them; and, in addition, we have elevators and depressors. 

 The muscle, shown in the preceding Fig. 2 (Nasalis longus 

 labii superioris), is most efficient in curling and elevating 

 the upper lip so as to grasp food. There is one on each side, 

 and the two join at the point of the nose, to form the broad 

 tendinous insertion Y. 



The tongue has intrinsic and extrinsic muscles. The 

 intrinsic are especially destined for the local movements of 

 the tongue, favourable to the movements of food within the 

 mouth. The extrinsic are connected with the tongue bone 

 os-hyoides and chin, and favour the protrusion and retraction 

 of the tongue, in the prehension of liquids as well as solids. 

 The membrane covering the tongue is provided with emin- 

 ences, or papillae, destined to increase its surface, for the 

 production of the protecting scaly epithelium. It is this pro- 

 tecting covering which acquires a horny hardness in the cat or 

 lion, whereby the action of the tongue may be compared to that 



