MOTIONS OF ANIMALS. 103 



kind of motions which their mode of life requires. Thus, in 

 monkeys and apes, which subsist principally upon the fruit 

 of trees, and, in fact, make them for the most part their place 

 of residence, in order to avoid the destruction to which they 

 are constantly exposed from beasts of prey, the limbs are par- 

 ticularly adapted for climbing. Upon plain ground they 

 seem to go with ease neither upon four legs nor two. In the 

 kangaroos, the hind legs are so long in proportion to those 

 before, that they are scarcely able to go on all fours, but move 

 from place to place principally by means of immense leaps, 

 which the great strength of their hind legs enables them to 

 make with facility. In the woodpecker, parrot, &c., whose 

 food obliges them to climb along the trunks and branches of 

 trees in search of it, the toes are particularly adapted for 

 climbing ; and in the waders, who go into very deep water 

 in quest of their prey, the legs are of very great length and 

 nearly destitute jof feathers. Examples of this kind might be 

 multiplied to a great extent.' 



The motions of animals are proportioned to their weight 

 and structure. A flea can leap some hundred times its own 

 length. Were an elephant, a camel, or a horse, to leap in 

 the same proportion, their weight would crush them to atoms. 

 The same remark is applicable to spiders, worms, and other 

 insects. The softness of their texture, and the comparative 

 smallness of their specific gravity, enable them to fall with 

 impunity from heights that would prove fatal to larger and 

 heavier animals. 



The different movements to which animals are stimulated 

 by the desire of food, by the appetite lor frolic and exercise, 

 by their hostilities, and by other exciting causes, give anima- 

 tion and vivacity to the whole scene of nature. A silent and 

 motionless prospect, however beautiful and variegated, soon 

 ceases to please, and at last becomes insupportable. Motion, 

 says Mr. Harris, is the object or cause of all sensation. In 

 music we hear it; in savors we taste it; in odors we smell it; 

 in touch we feel it ; in light we see it. 



Animals, furnished with destructive weapons, or endowed 

 with uncommon strength, courage, or ingenuity, are propor- 

 tionally slower in their movements than the weaker kinds. 

 The same remark is applicable to those species whose food is 

 always at hand. Worms, caterpillars, and many other in- 

 sects, in order to procure nourishment, are under no neces- 

 sity of taking an extensive range. But the motions of birds 

 and fishes are extremely rapid ; because, in quest of food, 



