Isolation and Selection 171 



natural selection and physical heredity. Moreover, it 

 is contrasted with natural selection on a point of which 

 Professor Hutton speaks. He says : * Natural Selection 

 is not truly selection, for the individuals can hardly be 

 said to select themselves by their superior strength, cun- 

 ning, or what not.' Now, * organic selection ' supposes 

 them doing this, in an important sense. It is a sort of 

 artificial selection put in the Jiands of the animal himself — 

 that is, so far as the re stilts go} 



As to 'isolation' (Professor Hutton's other topic), it is 

 certainly important, but is Professor Hutton right in con- 

 sidering it a positive cause } He says : * It is isolation 

 which produces the new race ; selection merely determines 

 the direction the new race is to take,* and 'isolation is 

 capable of originating new species.' But how } Suppose 

 we isolate some senile animals, or some physiological 

 minors, will a new race arise } The real cause in it all is 

 reproduction, heredity, with its likenesses and its varia- 

 tions. Both isolation and natural selection are negative 

 conditions : what are called in physical science ' control ' 

 conditions, of the operation of heredity. So in seeking 

 out such principles as 'selection,* 'isolation,' etc., we are 

 asking how heredity has been controlled, directed, diverted, 

 in this direction or that. Isolation is as purely negative 

 as is natural selection. Any influence which throws this 

 and that mate together in so far isolates them from others, 

 as has been said in a notice of Romanes' and Gulick's doc- 

 trine of isolation,^ and inasmuch as certain of these con- 

 trol conditions have already been discovered and otherwise 

 named by their discoverer as 'natural selection,' 'artificial 



1 See below, Chap. XIII. § i. 



2 Psychological Review, March, 1898, p. 216 (see Appendix C). 



