418 THE METHOD OF ORGANIC EVOLUTION. 



beeu recorded in all parts of tlie world. These are arranged systematic- 

 ally under nearly nine Imndred numbered headings, and are in many 

 cases well illustrated by cliaracteristic figures. The character and mor- 

 phological relations of these variations are often very fully discussed 

 with great knowledge and acuteness, and some original views are set 

 forth which are of interest both to morphologists and physiologists. 

 So far as this part of the work is concerned the present writer would 

 feel himself quite incompetent to criticise it, but would welcome it as 

 presenting in aconveuieut form a great body of interesting and little- 

 known facts. But the book goes far beyond this. The first words of the 

 preface tell us that ^'This book is offered as a contribution to the study 

 of the problem of species;" and in a lengthy introductory and shorter 

 concluding chapters this problem is discussed in some detail, with the 

 view of discrediting the views held by most Darwinians; while a new 

 theory, founded upon the facts given in the body of the work, is set 

 forth as being a more probable one. It is therefore necessary to give 

 some account of the nature of the facts themselves, as well as of the 

 particular theories they are held to support. 



Darwin distinguished two classes of variations, which he termed 

 "individual differences" and "sports." The former are small but 

 exceedingly numerous, the latter large but comparatively rare, and these 

 last are the "discontinuous variations" of Mr. Bateson to which refer- 

 ence has been already made. Darwin, while always believing that indi- 

 vidual differences played the most important part in the origin of species, 

 did not altogether exclude sports or discontinuous variations, but he 

 soon became convinced that these latter were quite unimportant, and 

 that they rarely, if ever, served to originate new species; and this view 

 is held by most of his followers. Mr. Bateson, however, seems to 

 believe that the exact contrary is the fact, and that sports or discon- 

 tinuous variations are the all-important, if not the exclusive, means by 

 which the organic world has been modified. Such a complete change 

 of base as to the method of organic evolution deserves, therefore, to be 

 considered in some detail. 



The difficulty which seems to have struck Mr. Bateson most, and 

 which he declares to be of "immense significance," is that while spe- 

 cific forms of life form a discontinuous series, the diverse environments 

 on whicli these primarily depend shade into each other insensibly, and 

 form a continuous series (p. 5). Further on this objection is again 

 urged in stronger language: "We have seen that the differences 

 between species are specific, and are differences of kind, forming a 

 discontinuous series, while the diversities of environment to which they 

 are subject are on the whole differences of degree, and form a continu- 

 ous series; it is therefore hard to see how the environmental differences 

 can thus be in any sense the directing cause of specific differences, 

 which by the theory of natural selection they should be" (p. 16). 

 Again, at page 09, he urges that the essential character of species is 



