from slighter variations/ 7 



He frequently repeats this statement and it is q 

 clear that he intends to convey the idea that all va 

 tions are merely quantitative; at any rate he fa 

 to adopt a nomenclature that would enable his rea< 

 to judge as to the degrees of difference he meant 

 indicate by such adjectives as "insensible," "minul 

 "slight," "large," "wide," "sudden" and "abruj 

 as applied to variations. I am convinced, however, l 

 he had in mind an idea that there were two dit'fei 

 kinds of variations, namely, first, what he oft ones t ea 

 "individual variations," by which he referred to 

 ordinary differences between the single organisms of 

 same group, or what mutationists now call "fluctuatior 

 and, second, those radical and generally extensive de 

 tions from type which constitute an actual break 

 the species, variety or race, and which are substantii 

 what we of these later times have named "mutatior 

 There are places in Darwin's works where the two ki 

 of variation just mentioned are spoken of as "indefini 

 and "definite" and as results, respectively, of the indii 

 and the direct action of the conditions of life, and o 

 only, I think, he uses the term "fluctuating variabili 

 as synonymous with indefinite variability. 28 Now I 

 not assume to say that the recognition of these dist 

 tions by Mr. Darwin proves that he clearly foresaw 

 present-day mutation theory with its foundation in 

 principle of unit characters, but I think it is true t 

 he had at least a glimpse of the coming modificati 



and Plantf Under ^Domestication, ^2d ed., Vol. I, pp. 312, 322. 



