REFLEXES, INSTINCT, AND REASON 445 



On the open plains of Merced County, Cal., the jack rabbit 

 is the prey of the bald eagle. Not long since a rabbit pursued 

 by an eagle was seen to run among the cattle. Leaping from 

 cow to cow, he used these animals as a shelter from the savage 

 bird. When the pursuit was closer, the rabbit broke cover 

 for a barbed- wire fence. When the eagle swooped down on it, 

 the rabbit moved a few inches to the right, and the eagle could 

 not reach him through the fence. When the eagle came down 

 on the other side, he moved across to the first. And this was 

 continued until the eagle gave up the chase. It is instinct 

 that leads the eagle to swoop on the rabbit. It is instinct again 

 for the rabbit to run away. But to run along the line of a 

 barbed-wire fence demands some degree of reason. If the need 

 to repeat it arose often in the lifetime of a single rabbit it would 

 become a habit. 



The difference between intellect and instinct in lower animals 

 may be illustrated by the conduct of certain monkeys brought 

 into relation with new experiences. At one time we had two 

 adult monkeys, "Bob' and "Jocko/' belonging to the genus 

 Macacus. Neither of these possessed the egg-eating instinct. 

 At the same time we had a baby monkey, " Mono," of the genus 

 Cercopithecus. Mono had never seen an egg, but his inherited 

 impulses bore a direct relation to feeding on eggs, just as the 

 heredity of Macacus taught the others how to crack nuts or 

 to peel fruit. 



To each of these monkeys we gave an egg, the first that any 

 of them had ever seen. The baby monkey, Mono, being of an 

 egg-eating race, devoured his egg by the operation of instinct 

 or inherited habit. On being given the egg for the first time, 

 he cracked it with his upper teeth, making a hole in it, and sucked 

 out all the substance. Then holding the eggshell up to the 

 light and seeing that there was no longer anything in it, he 

 threw it away. All this he did mechanically, automatically, 

 and it was just as well done with the first egg he ever saw as 

 with any other he ate. All eggs since offered him he has trea.ted 

 in the same wav. 



/ 



The monkey Bob took the egg for some kind of nut. He 

 broke it against his upper teeth and tried to pull off the shell, 

 when the inside ran out and fell on the ground. He looked at it 

 for a moment in bewilderment, took both hands and scooped up 

 the yolk and the sand with which it was mixed and swallowed 



