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FOREWORD 



For three-quarters of a century past more has been written about 

 natural selection and the struggle for existence that underlies the 

 selective process, than perhaps about any other single idea in the 

 whole realm of biology. We have seen natural selection laid on its 

 Sterbebett, and subsequently revived again in the most recent times 

 to a remarkable degree of vigor. There can be no doubt that the 

 old idea has great survival value. 



The odd thing about the case, however, is that during all the years 

 from 1859, when Darwin assembled in the Origin of Species a masterly 

 array of concrete evidence for the reality of the struggle for existence 

 and the process of natural selection, down to the present day, about 

 all that biologists, by and large, have done regarding the idea is to 

 talk and write. If ever an idea cried and begged for experimental 

 testing and development, surely it was this one. Yet the whole array 

 of experimental and statistical attempts in all these years to produce 

 some significant new evidence about the nature and consequences of 

 the struggle for existence is pitifully meager. Such contributions as 

 those of Bumpus, Weldon, Pearson, and Harris are worthy of all 

 praise, but there have been so very, very few of them. And there is 

 surely something comic in the spectacle of laboratories overtly em- 

 barking upon the experimental study of evolution and carefully 

 thereafter avoiding any direct and purposeful attack upon a pertinent 

 problem, the fundamental importance of which Darwin surely estab- 

 lished. 



At the present time there is abundant evidence of an altered atti- 

 tude; and particularly among the younger generation of biologists. 

 The problem is being attacked, frontally, vigorously and intelligently. 

 This renewed and effective activity seems to be due primarily to two 

 things : first, the recrudescence of general interest in the problems of 

 population, with the accompanying recognition that population 

 problems are basically biological problems; and, second, the realiza- 

 tion that the struggle for existence and natural selection are matters 

 concerning the dynamics of populations, birth rates, death rates, 

 interactions of mixed populations, etc. These things were recognized 



