ANIMAL 



261 



ANIMAL 



fly to one of another color when there is no 

 other difference; but most insects, it is prob- 

 able, see but poorly. 



Hearing. The sense of hearing is no more 

 evenly distributed than that of sight, but in 

 general it may be said that the higher animals 

 have it in far greater perfection than the lower. 

 The horse traveling the flinty road hears the 

 hoof-beats of another horse approaching him 

 before the sound reaches his driver's ears; the 

 h dog pricks up his ears at a noise which 

 is inaudible to every human inmate of the 

 house. It was long believed that fish were 

 entirely deaf, but it seems to be an estab- 

 h~h.il fact that some sounds do reach them, 

 though probably not enough to make neces- 

 sary the "silence" warning to fishermen. 



Touch. The sense of touch does for some 

 animals much that the sense of sight does for 

 man. The "feelers" of certain insects, the 

 whiskers of the cat these are special touch 

 organs developed through long usage. A dog's 

 ears seem to be the most sensitive part of its 

 anatomy, while in a bat the wing membrane 

 responds to the slightest touch. 



Taste. Here again it is almost impossible 

 to speak with accuracy, for while it is certain 

 that animals delight in one kind of food and 

 reject another, it is probable that smell rather 



than taste guides them. The two are very 

 closely connected, even in man; and the per- 

 son who has absolutely lost his sense of smell 

 can distinguish only sweet, sour, bitter and 

 salt. That there is some sense of taste even 

 in the lower forms of life is proved by the 

 fact that insects can tell sweet from bitter 

 a distinction probably not made by the sense 

 of smell. 



Smell. Everybody is familiar with the fact 

 that some animals have an almost incredibly 

 keen sense of smell. That of most dogs is so 

 acute as to enable them to recognize people 

 whom them have once seen, and certain spe- 

 cies of dogs can track a person by scent, even 

 when the trail is crossed by numerous others. 

 A deer, too, when the wind is right, can detect 

 the presence of man before eye or ear makes 

 it evident. In no other members of the ani- 

 mal kingdom is the sense of smell more pro- 

 nounced than in insects. It is because of this 

 fact that flowers have developed fragrance 

 that they may attract to themselves the insect 

 visitors so necessary to their complete life. 

 A new bee in a hive does not need to be 

 guided to the nearest locust-grove; the sweet 

 scent is sufficient guide. On the other hand, 

 birds, reptiles and most fish depend very little 

 on their sense of smell. V.L.K. 



Migration of Animals 



This is a term used to denote first, the irreg- 

 ular overflow of such animals as mice, lem- 

 mings, locusts and chinch bugs from their 

 more usual range, and second, the periodic 

 movements of fishes, birds, seal and many 

 other animals at the changes of season. As 

 these two classes of movements are different 

 in character, they are discussed separately 

 below. 



Irregular Overflows. The movements of the 

 1' mining, a rat-like animal found mostly in 

 Norway and Sweden, furnish a good example 

 of this class. At irregular intervals of five to 

 twenty years great hordes of lemmings leave 

 th'-ir homes and travel toward the sea. The 

 mation seems to be that they multiply 

 so rapidly that the food supply in tin- vicinity 

 of their homes becomes too small. Then the 

 excess of animals must wander off to otln-r 

 >ns; instinctively they move for the pre- 

 servation of the species. 



A similar explanation accounts for the 

 I ! miles of mice and Rocky Mountain locusts 

 which occasionally ruin thousands of acres of 



grain on the plains of North America. Flies, 

 chinch bugs, army worms, rabbits, antelopes 

 and other animals are known to travel far in 

 search of feeding grounds, and these acquired 

 locations become their new homes. 



Periodic Migrations. Many animals migrate 

 two or more times a year, the temperature 

 and food supply determining the time and ex- 

 tent of such movements. At the approach 

 of spring the mountain sheep and goats leave 

 the regibns in which they have spent the 

 winter and climb upward to the cooler alti- 

 tudes. Each autumn the caribou travels from 

 his haunts near the Arctic Ocean to the wanner 

 regions around Hudson Bay, and each spring 

 he reverses this course. Years ago, when tin- 

 buffaloes were still plentiful, their herds wan- 

 dered north or south with the changing sea- 

 sons. Whales, especially the sperm whales, 

 have regular courses along the coasts of North 

 America. 



Some of the most remarkable migrations are 

 those of fishes, especially the salmon, wl 

 ascend and descend rivers, even through rapids 



