390 ANIMAL STUDIES 



It is not necessary to consider here the question of the 

 origin of instincts. Some writers regard them as " inherited 

 habits," while others, with apparent justice, doubt if mere 

 habits or voluntary actions repeated till they become a 

 " second nature " ever leave a trace upon heredity. Such 

 investigators regard instinct as the natural survival of those 

 methods of automatic response which were most useful to 

 the life of the animal, the individuals having less effective 

 methods of reflex action having perished, leaving no pos- 

 terity. 



An example in point would be the homing instinct of 

 the fur-seal. When the arctic winter descends on its home 

 in the Pribilof Islands in Bering Sea, these animals take 

 to the open ocean, many of them swimming southward as 

 far as the Santa Barbara Islands in California, more than 

 three thousand miles from home. While on the long swim 

 they never go on shore, but in the spring they return to 

 the northward, finding the little islands hidden in the arc- 

 tic fogs, often landing on the very spot from which they 

 were driven by the ice six months before, and their arrival 

 timed from year to year almost to the same day. The per- 

 fection of this homing instinct is vital to their life. If 

 defective in any individual, he would be lost to the herd 

 and would leave no descendants. Those who return be- 

 come the parents of the herd. As to the others the rough 

 sea tells no tales. We know that, of those that set forth, a 

 large percentage never comes back. To those that return 

 the homing instinct has proved adequate. This must be so 

 so long as the race exists. The failure of instinct would 

 mean the extinction of the species. 



303. Classification of instincts. The instincts of animals 

 may be roughly classified as to their relation to the indi- 

 vidual into egoistic and altruistic instincts. 



Egoistic instincts are those which concern chiefly the 

 individual animal itself. To this class belong the instincts 

 of feeding, those of self-defense and of strife, the instincts 



