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 shown 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 



