PEEHENSION OF FOOD. 163 



and fatty ^ matters, termed chyle, is separated from the matters 

 that are to be thrown off : this process, which is the second 

 stage of true digestion, is termed chylification. The rejected 

 portions of the food, with secretions poured into the alimen- 

 tary canal, find their way out through the intestinal tube ; 

 and are voided at its terminal orifice by the act of defecation. 

 And lastly, the nutritive materials are taken up by absorption 

 into vessels that are distributed upon the walls of the diges- 

 tive cavity, and undergo a gradual change, by which they are 

 converted into blood. These two processes are called absorp- 

 tion and sanguification (or manufacture of blood). Each of 

 the foregoing stages will now be separately considered. 



Prehension of Food. 



172. The introduction of aliment within the entrance to the 

 digestive cavity is accomplished in various methods in dif- 

 ferent animals. In the Mammalia in general, the aperture of 

 whose mouth is guarded by fleshy lips, these, with the jaws 

 and teeth, are the chief instruments of this operation. But 

 in Man and the Monkey tribe the division of labour is 

 carried further ; the food being laid hold of by the anterior 

 members, or hands, and by them carried to the mouth. 

 "Where the hand has the power of grasping, and especially 

 where the thumb can be opposed to the fingers, the action of a 

 single member is sufficient j but there are several animals 

 which, like the Squirrel, use both limbs conjointly to hold 

 their food, the extremity not having itself the power of grasp- 

 ing. The Ant-eaters, Woodpeckers, Chameleons, and other 

 insect-eating animals, obtain their food 

 by means of a long extensible tongue ; 

 this either serving to transfix the insect, 

 or being covered with a viscid saliva 

 which glues it to the surface. The Giraffe 

 uses its long tongue to lay hold of the 

 young shoots on which it browses ; and 

 the Elephant employs its trunk, which is 

 nothing else than a prolonged nose, for 

 every kind of prehension (fig. 82). Many 

 of the Invertebrata are furnished with 



T, ji T -, , -, . ,1 -i HEAD OF ELEPHANT. 



little appendages round their mouths by 



which the food is conveyed into them ; such are the palpi 



M2 



