n8 THE THEORY OF MUTATION 



of no small importance in disposing of many minor 

 objections to the doctrine of transmutation.'* 



The first person to formulate a more or less precise 

 view upon the subject of definite variation was Francis 

 Gait on, although this author never entered into the 

 question at any great length. Galton's attitude 

 towards the problem in its early stages may be gathered 

 from the following quotation from his ' Natural In- 

 heritance ': * The theory of natural selection might 

 dispense with a restriction for which it is difficult to 

 see either the need or the justification namely, that 

 the course of evolution always proceeds by steps that 

 are severally minute, and that become effective only 

 through accumulation. That the steps may be small, 

 and that they must be small, are very different views ; 

 it is only to the latter that I object, and only when the 

 indefinite word " small " is used in the sense of " barely 

 discernible," or as small compared with such large sports 

 as are known to have been the origins of new races. 'f 



But more than this, the idea of the existence of 

 stable forms, such as may be supposed to have arisen 

 by large and sudden variations, is very well expressed 

 by Galton in his division of varieties into the three 

 groups of primary types, subordinate types, and mere 

 deviations from the latter. A most luminous analogy 

 is afforded by the three types of public vehicles which 

 at the end of the nineteenth century were character- 

 istic of the streets of London ; and it is impossible to 

 resist quoting Galton's account of them. These three 



* ' Collected Essays,' vol. ii., p. 77. 

 t ' Natural Inheritance,' p. 32. 



