126 THE EVOLUTION THEORY 



let us say plus — meet together, the plus-variation of X must be all the 

 more sharply emphasized in the child. 



Thus, altliough the individual determinants X may not be incited 

 to furtlier variation by their co-operation with others varying in the 

 same direction, the collective effect of the plus- determinants W'ill be 

 greater, and adherence to the same direction of variation in the 

 following generation will be assured, for if in the germ-plasm of the 

 parent there be, for instance, sixteen out of twenty determinants 

 possessing the plus-variation, a minus-majorit}^ can no longer result 

 from reducing division. 



It is upon this that the operation of natural selection, that is, 

 personal selection, must depend — that the germ-plasms in wliich the 

 favourable variation-direction is in the majority are selected for 

 breeding, for it is this and nothing else that natural selection does 

 when it selects the individuals which possess the preferred variations. 

 The ascending process is thus considerably advanced, because the 

 opposing determinants are more and more eliminated from the germ- 

 plasm, till the preferred variations of X are left, and among these, as 

 ascent in the direction begun continues, the opposing variations are 

 again set aside by germinal selection, and so on. Reducing divisions 

 and amphimixis are thus powerful factors in furthering the trans- 

 formations of tlie forms of life, altliougli they are not tlie ultimate 

 causes of these. 



Now that we have made ourselves familiar with the idea of 

 germinal selection we shall attempt to gain clearness as to what it can 

 do, and how far the sphere of its influence extends, and, in particular, 

 whether it can effect lasting transformations of species without the 

 co-operation of personal selection, and what kind of variations we ma}^ 

 ascribe to it alone. 



First, I nnist return for a moment to the question we have 

 already briefly discussed — whether the variation of a determinant 

 upwards or downwards must so continue without limit. We might 

 be inclined to think that the great constancy which many species 

 exhibit was a plain contradiction of this, for if every minute variation 

 of a determinant necessarily persisted without limit in the same 

 direction, we should expect to find all the parts of the organism in 

 a state of continual unrest, some varj^ing upwards, some downwards, 

 always ready to break the tj^pe of the species. Must there not be 

 some internal self-regulation of the germ-plasm wliich makes it 

 impossible that every variation which crops up can persist unlimit- 

 edly ? Must there not be some kind of automatic control on the j^art 

 of the germ-plasm, which is always striving to re-establish the state 



