66 Mutability and Individual Variation. 



Bateson's conclusion is expressed in the following 

 words : The evidence of variation suggests in brief, that 

 the discontinuity of species residts from the discontinuity 

 of variation.^ 



W. B. Scott, in an exhaustive critique, has expressed 

 his opposition to many of the views in Bateson's book.- 

 He particularly objects to the statement that species form 

 a discontinuous series. He adduces recent paleontolog- 

 ical discoveries as proof that there are no such gaps in 

 the genealogical trees of the horses or of many other 

 mammals. Such series are only discontinuous when our 

 knowledge concerning them is incomplete. In contin- 

 uous series the progression took place by almost imper- 

 ceptible gradations.^ These gradations seem, however, 

 to be what Bateson calls steps. Let us return to the 

 simile of Galton's rolling polyhedron. The question 

 whether we choose to call this movement continuous or 

 discontinuous depends on our point of view. Even a 

 series of numbers can be unbroken and therefore con- 

 tinuous. 



The word mutation has been used more in paleon- 

 tology than in other sciences to express the differences 

 between allied species. The actual process of mutation, 

 the change of one species into another, can obviously 

 not form a problem of paleontology. The paleontol- 

 ogist can only study the series of consecutive forms. 

 From such series however important information may be 

 derived as to the size of individual steps, that is to say, 

 the mutations. Waagen has said that the more com- 

 plete the geological evidence is the less perceptible do 



'^ Loc. cit., p. 568. 



"W. B. Scott, On Variations and Mutations. Am. Journ. Sci., 

 8° series, vol. 48, Nov. 1894, PP- 355-374- 

 ^ Page 360. 



