212 THE ZOOLOGIST. 



fectly or permanently, for the same reason given for the others 

 — nosing and climbing impulses. 



VI. 



It seems not improbable that the evolution of the capacity 

 for habit formation has taken the following stages : — 



1. Where there is no modifiability of behaviour. 



2. Where modifiability does exist, but in only a slight degree, 

 so that habits become formed only after a long period of 

 " stamping in." On account of this protracted period of 

 " stamping in," useless habits cannot be reduced, and therefore 

 correct habits are not formed, although roundabout methods 

 of solving the problems presented are adopted. 



3. Where there is rapid modifiability, succeeded by a more 

 or less rapid reduction of useless habits. The very fact 

 of rapid modifiability makes reduction possible. But rapid 

 modifiability, in its inception, consists of the tendency mechani- 

 cally to repeat movements from which pleasure need not 

 necessarily result. Thus a large number of useless habits 

 would make their appearance, and the first solution of a problem 

 would be a very roundabout one. Subsequent experience would 

 reduce the number, and different animals, varying in intelligence, 

 would vary in the rapidity with which they were reduced. 



4. Where a keener consciousness and a more acute intelli- 

 gence means rapid modifiability, but, more particularly, few 

 useless habits, as only movements ending in pleasure would 

 tend to be impressed on the nerve centres, and therefore to be 

 repeated. The relative intelligence of different animals in this 

 category would depend upon the rapidity of their perceptions of 

 those movements most conducive to pleasure, i. e. upon the 

 paucity of useless habits formed in the first instance. 



5. Where, finally, modifiability is more or less immediate, 

 through the presence of the memory idea, absent in the others. 



The first class is perhaps hypothetical, perhaps the Crab 

 belongs to the second, while the third class is represented by the 

 Newt, the fourth by the Pigeon, and the last by Man. All these 

 animals have had their learning powers tested. This course of 

 development would involve the formation of useless habits, not as 

 a freak of intelligence, but as a natural sequence in the order of 



