1909. Reviews. 237 



THE EVOLUTION PROBLEM. 



The Wlaking of Species. By Dougi,as Dewar, B.A. (Cantab.), 

 I.CvS., F.Z.S., and Frank Finn, B.A. (Oxon.), F.Z.S., M.B.O.U. 

 With fifteen illustrations. Pp. 400. London : John Lane. Price 

 "js. 6d. net. 



The authors of this book are strong champions of " discontinuous 

 variation," and remorseless enemies to all exaggerated belief in the 

 potency of Natural Selection. They pin their faith on the origin of 

 species through sudden jumps or "mutations," and much interesting 

 matter is adduced by them in support of their application to the animal 

 world of a modified form of the theory put forward by De Vries with 

 special relation to plants. The extensive and critical knowledge which 

 both authors possess of the natiiral history of India enables them to 

 supplement largel}' from their own store of observations the mass of 

 more generally known facts having a bearing on the question. In its 

 main lines the argument is well calculated to impress. Indeed, the case 

 for a very large pla}' of discontinuous variation in evolution has rarely, if 

 ever, been better put in a book adapted for general reading. 



In presenting the negative side of their case the authors adopt a rather 

 more warlike tone than the contents of the book justif}-. They do not 

 make it quite clear what part they would themselves allow Natural Selec- 

 tion to play. We are told that she has a '•' casting vote " on the question 

 whether a new mutation is to survive or perish ; but the extent of any 

 further concession to Darwinism ('*' Neo-" or otherwise) is left obscure. 

 Roughly speaking, the line seems to be taken that no special contrivance 

 in nature can be accounted for by the favour shown to its incipient 

 stages. Positive utility, in many of its more marked phases, is acknow- 

 ledged as a fact, but held to be accidental. The authors speciall}^ attack 

 the doctrines of protective or obliterative colour, of warning colour, of 

 mimicry, and of the adaptation of flowers to secure cross-fertilisation. 

 Here, we think, they weaken and harm their case. The view which the 

 reader is asked to take is one that violates his sense of proportion. 



In disputing, for instance, the view that the colours of flowers have 

 any special relation to the object of attracting insects to secure cross- 

 fertilisation, Messrs. Dewar and Finn challenge what they call the 

 assumption that cross-fertilisation is advantageous to plants, and bring 

 forward some arguments tending to show that self- fertilisation is really 

 the more serviceable process. On this view the workings of Nature 

 must have been veritably paradoxical. Self-fertilisation was undoubtedly 

 the primitive process throughout the floral world. The great advantages 

 that it does secure are obvious, so much so that it would have seemed 

 inconceivable in a world where no other method was followed that 

 plants could even depart from it. Yet we see throughout the phanero- 

 gamic world, and especialh' among the more highly developed orders of 

 plants, the most varied and elaborate contrivances to prevent it, and to 

 secure cross-fertilisation in its stead. Is it credible that all these com- 

 plex and ingenious devices, serving in so many ways the same end, have 



