DISCONTINUOUS VARIATIONS 85 



tinuously passing from one guise to another by transilient 

 variation. 



Mr. Bateson (1905, p. 577) notes that Marchant in 1719 was 

 the earliest to comment on the suggestiveness of sudden changes, 

 such as he saw in plants of Mercurialis with laciniated and hair- 

 like leaves which for a time established themselves in his garden. 

 He suggested that species may arise in like manner. " Though 

 the same conclusion has appeared inevitable to many, including 

 authorities of very diverse experience, such as Huxley, Virchow, 

 F. Galton, it has been strenuously resisted by the bulk of scientific 

 opinion, especially in England. 



" Upon whatever character the attention be fixed, whether 

 size, number, form of the whole or of the parts, proportion, 

 distribution of differentiation, sexual characters, fertility, pre- 

 cocity or lateness, colour, susceptibility to cold or to disease — 

 in short, all the kinds of characters which we think of as best 

 exemplifying specific difference, we are certain to find illustrations 

 of the occurrence of departures from normality, presenting ex- 

 actly the same definiteness elsewhere characteristic of normality 

 itself. Again and again the circumstances of their occurrence 

 render it impossible to suppose that these striking differences 

 are the product of continued selection, or, indeed, that they 

 represent the results of a gradual transformation of any kind. 

 Whenever by any collocation of favouring circumstances such 

 definite novelties possess a superior viability, supplanting 

 their ' normal ' relatives, it is obvious that new types will be 

 created." 



Heredity and Evolution.— Mr. Bateson has done good 

 service in exposing to ridicule the prevalent misconception that 

 domesticated races are " so many incarnations of the breeder's 

 prophetic fancy." " Except in recombinations of pre-existing 

 characters — now a comprehensible process — and in such intensi- 

 fications and such finishing touches as involve variations which 

 analogy makes probable, the part played by prophecy is small 



