72 INTELLIGENCE AND INSTINCT 



Some of them collect only honey and wax ; while others 

 are charged with the care and education of the young ; and 

 still others are the natural chiefs of the colony. 



144. Finally, there are certain animals so guided by their 

 instinct as to live like pirates, on the avails of others' 

 labor. The Lestris or Jager will not take the trouble to 

 catch fish for itself, but pursues the gulls, until, worn out 

 by the pursuit, they eject their prey from their crop. Some 

 ants make war upon others less powerful, take their young 

 away to their nests, and oblige them to labor in slavery. 



145. There is a striking relation between the volume of 

 the brain compared with the body, and the degree of intelli- 

 gence which an animal may attain. The brain of man is 

 the most voluminous of all, and among other animals there is 

 every gradation in this respect. In general, an animal is the 

 more intelligent, in proportion as its brain bears a greater 

 resemblance to that of man. 



146. The relation between instinct and the nervous 

 system does not present so intimate a correspondence as 

 exists between the intellect and the brain. Animals which 

 have a most striking development of instinct, as the ants and 

 bees, belong to a division of the Animal Kingdom where the 

 nervous system is much less developed than that of the ver- 

 tebrates, since they have only ganglions, without a proper 

 brain. There is even a certain antagonism between instinct 

 and intelligence, so that instinct loses its force and peculiar 

 character, whenever intelligence becomes developed. 



147. Instinct plays but a secondary part in man. He is 

 not, however, entirely devoid of it. Some of his actions are 

 entirely prompted by instinct, as, for instance, the attempts of 

 the infant to nurse. The fact, again, that these instinctive 

 actions mostly belong to infancy, when intelligence is but 

 slightly developed, goes to confirm the two last propositions. 



