Habit and Instinct. 447 



and a thousand other modifications and divergences of 

 habit, I question whether the theory that they have all 

 arisen through the elimination of those forms which failed 

 to possess them may not be pushed too far ; I am inclined 

 to believe that the inheritance of acquired modifications 

 has been a co-operating factor. It is not enough to say 

 that these habits are all useful to their several possessors. 

 It has to be shoivn that they are of elimination value — that 

 their possession or non-possession has made all the differ- 

 ence between survival and elimination. 



On the whole, then, as the result of a careful considera- 

 tion of the subject of instinctive and habitual activities, 

 and in accordance with my general view of organic evolu- 

 tion as set forth in previous chapters, I am disposed to 

 accept the inheritance of individually acquired modifications 

 of habit as a working hypothesis. I do not think that 

 absolutely convincing evidence thereof can at present be 

 produced. But to the best of my judgment, the probabili- 

 ties are in favour of the inheritance of modifications of 

 existing activities, due to intelligence, instruction, and 

 imitation ; always provided that the exercise of these 

 modified activities is sufficiently frequent and definite to 

 give rise to habits in the individual. 



I recognize three factors in the origin of instinctive 

 activities — 



1. Elimination through natural selection. 



2. Selection through preferential mating. 



3. The inheritance of individually acquired modifica- 

 tions. 



Of these I consider the first quite incontrovertible ; the 

 second as highly probable ; and the third as probable in a 

 less degree. In all three, intelligence may or may not have 

 been a factor. Some of the habits which have survived 

 elimination under the first factor may have been originally 

 intelligent, some of them from the first unintelligent. 

 Some of the love-antics (so called), which, through their 

 tendency to excite sexual appetence in the female, have 

 been selected under the second factor, may have had a 



