MOTIONS OF ANIMALS- J ; '~ 101 



animals. They constitute the greater .part of the; laedr, which 

 is served up to us as food. In quadrupeds and someTparfe of 

 birds, this is red ; in fishes and most of the lower orders of 

 animals, it is white. It may be distinguished from other parts 

 by its fibrous or stringy texture, which is more or less distinct, 

 according to the size, strength, and moving powers of the ani- 

 mal to which it belongs, and in some is scarcely to be ob- 

 served at all. The contraction of muscles, and the consequent 

 motions of the different organs, depend upon some unknown 

 influence derived to them from the brain and nerves. Hence- 

 the brain and nerves are the sources of every motion, as well 

 as of every sensation. With regard to the causes which de- 

 termine the actions of animals, these must be referred to sen- 

 sation, and the consequent exertions of intellect. The first 

 impression an object makes upon our senses stimulates us 

 either to approach or retire from it, according as it excites 

 affection or aversion. But man, and many other animals, 

 have the power of resisting these original motives to action, 

 and of remaining at rest, without either retiring or approaching. 

 ''If a man," says the Count de Buffon, " were deprived of 

 sight, he would make no movement to gratify his eyes. The 

 same thing would happen, if he were deprived of any of the 

 other senses ; and, if deprived of every sense, he would re- 

 main perpetually at rest, and no object would excite him to 

 move, though, by natural conformation, he were fully capable 

 of motion." Natural wants, as that of taking nourishment, 

 necessarily excite desire or appetite. But if a man be de- 

 prived of sensation, want cannot exist, because all its sources 

 are annihilated. An animal without some sensation is no 

 animal, but a dead mass of matter. Sensation is the only 

 stimulus to animal motion : the aptness of the parts produces 

 the effect, which varies according to the structure and desti- 

 nation of these parts. The sense of want creates desire. 

 Whenever an animal perceives an object fitted to supply its 

 wants, desire is the necessary consequence, and action or 

 motion instantly succeeds. 



' With regard to motions of the second kind, or involuntary 

 motions, they are also performed by organs that commonly 

 possess muscular fibres, but they are not connected with 

 bones. The heart is a hollow muscle, which contracts in 

 every direction upon the blood, and consequently throws it 

 with great force into the arteries. The stomach is also a 

 hollow mascle, which acts upon its contents by contraction; 

 and the same is true of most of the internal organs where 

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