244 ANIMAL LIFE 



of play, the climatic instincts, and environmental instincts, 

 those which direct the animal's mode of life. 



Altruistic instincts are those which relate to parent- 

 hood and those which are concerned with the mass of indi- 

 viduals of the same species. The latter may be called the 

 social instincts. In the former class, the instincts of par- 

 enthood, may be included the instincts of courtship, re- 

 production, home-making, nest-building, and care for the 

 young. 



131. Feeding. The instincts of feeding are primitively 

 simple, growing complex through complex conditions. 

 The protozoan absorbs smaller creatures which contain 

 nutriment. The sea-anemone closes its tentacles over its 

 prey. The barnacle waves its feelers to bring edible crea- 

 tures within its mouth. The fish seizes its prey by direct 

 motion. The higher vertebrates in general do the same, 

 but the conditions of life modify this simple action to a 

 very great degree. 



In general, animals decide by reflex actions what is 

 suitable food, and by the same processes they reject poisons 

 or unsuitable substances. The dog rejects an apple, while 

 the horse rejects a piece of meat. Either will turn away 

 from an offered stone. Almost all animals reject poisons 

 instantly. Those who fail in this regard ' in a state of 

 nature die and leave no descendants. The wild vetches or 

 " loco-weeds " of the arid regions affect the nerve centers of 

 animals and cause dizziness or death. The native ponies 

 reject these instinctively. This may be because all ponies 

 which have not this reflex dislike have been destroyed. 

 The imported horse has no such instinct and is poisoned. 

 Very few animals will eat any poisonous object with which 

 their instincts are familiar, unless it be concealed from smell 

 and taste. 



In some cases,^very elaborate instincts arise in connec- 

 tion with feeding habits. \With the California woodpeckers 

 (Melanerpes formicivorus lairdii) a large number of them 



