ix ANIMAL BEHAVIOUR 171 



however, they cannot go out again, or give their fellow- 

 prisoners a hint how to escape. 



It must not be supposed, however, that animals of the 

 little-brain type are unable to profit by experience. We 

 know, in fact, that they build up complex chains of 

 associations, as some ants do in learning to find their 

 way home. Of twenty hive-bees which Prof. Yung of 

 Geneva took into the country for a distance of six kilo- 

 metres, seventeen returned to the hive. But when these 

 seventeen were taken next dav out on to the lake and 



*/ 



liberated there, none returned. There seems little doubt 

 that bees accumulate an acquaintance with certain fea- 

 tures of the countryside around their hive. 



9. Intelligent Behaviour. Among birds and mammals 

 in particular we find illustrations of a kind of behaviour 

 which it is difficult or impossible to describe without 

 using psychological terms. We see what looks like trial 

 and error experiment, adapting means to ends, profit- 

 ing by experience. We infer that it implies some " per- 

 ceptual inference," some " putting two and two to- 

 gether." some working with ideas. It is reflective and 

 experimental, as contrasted with instinctive and intui- 

 tive. 



When the Greek eagle lets the tortoise fall from a 

 height on the rocks below so that its strong carapace is 

 broken, when beavers cut a canal right through an island 

 in a big river a task not practically justified till com- 

 pleted, when a collie dog at the bidding of a few sounds 

 and signs accomplishes a really difficult thing in the way 

 of sheep-driving, it is probable that we have to do with 

 intelligent behaviour. 



When Romanes's chimpanzee was asked for a number 

 of straws up to five, it used to pick up the required num- 

 ber and present them with the ends exposed between 

 finger and thumb. When it was right it got its reward. 

 Sometimes, however, if asked for four straws, it would 

 gather three to save time, and double one of them, so 

 that four ends showed. When a reward was refused on 

 such occasions, it would straighten out the doubled 

 straw, pick up another one, and present the required 



