GERMINAL AND PERSONAL SELECTION 53 



progressively those individuals who do not possess them ; and 

 thus does natural selection tend to produce uniformity in the 

 germ-plasm within a given species under given conditions. The 

 more individuals of a species there are who possess a majority 

 of determinants A^, corresponding to a variation A, the less 

 chance is there of these determinants being ehminated in the 

 reduction of the ids at maturation or in amphimixis. 



But can germinal selection bring about lasting changes in the 

 character of a species without the co-operation of natural selec- 

 tion, or, as Weismann calls it, personal selection ? The answer 

 must be in the negative. Germinal selection is not by itself 

 capable of transforming a species, although it is the origin of 

 those variations which personal selection operates on in bringing 

 about such a transformation. By itself, germinal selection 

 can effect changes which possess a purely morphological value, 

 and which do not influence in any way the life of the individual 

 or the life of the species ; but once a variation has attained 

 selective value, such variation must either be maintained or 

 eradicated by the action of personal selection. 



For instance, the possession of six fingers on the hand, or of 

 a tiny scar behind the ear, does not in any way influence the 

 life of the individual in the struggle for existence ; consequently, 

 there is no reason for natural selection to intervene, either by 

 the maintenance or by the eradication of such abnormalities, 

 which have a purely morphological, as distinct from a biological, 

 value. Such variations are exclusively the work of germinal 

 selection, and their disappearance is effected solely by perturba- 

 tions of intragerminal nutrition in the germ-plasm. On the 

 other hand, the peculiar colouring of certain insects is the result 

 of adaptation to peculiar conditions of life, and is the work of 

 natural selection supplementing the action of germinal selection. 

 There is a certain species of butterfly, Phyllodes ornata, a native 

 of Assam, which shows the result of adaptation in a very highly 

 developed degree, although numerous equally significant cases 



