REFLEXES, INSTINCT, AND 1{I:aS()N J j.", 



On tlic oiH'ii ])laiiis of Merced County, Cal., the jack ral)bit 

 is the prey of the bald eagle. Not h)ng since a ra))bit pursued 

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

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

 bird. When the i)ursuit was closer, the; rabl>it* broke cover 

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

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

 not reach him tlirougli the fence. W hen the eagle came down 

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

 continued until the eagle gave uj) the chase. It is instiiu-t 

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

 for the rabbit to run away, l^ut to run along the line of a 

 bai bed-wire fence demands some degree of rea.son. If theneeil 

 to repeat it arose often in the lifetime of a single rabbit it woul«l 

 become a habit. 



The difference l^etween intellect and instinct in lower animals 

 mc\y be illustrated by the conduct of certain monkeys brought 

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

 adult monkeys, "Bob" and ".locko," belonging to the genus 

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

 At the same time we had a bab}' monkey, " Mono." of the genus 

 Cercopitheciis. Mono had never seen an egg. but his inl.e:ited 

 impulses bore a direct relation to feeding on eggs, just lus 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 o|)eration of instinct 

 or inherited hal)it. On being given the egg for the first time, 

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

 out all the substance. Then holding the eggshell uj) to th.e 

 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 lie ever siiw as 

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

 in the same way. 



The monkey Jiob look the egg for .some kind of nut. He 

 broke it against his upper teeth and tried to i»ull ofT tl»e .^iliell. 

 when the inside ran out and fell on the grouiul. He looketi at it 

 for a moment in bewilderm<'nt . took both hands and sc(M)Imm1 up 

 the volk and the sand with whifh it was mixcfl and swallowoi 



