132 THE EVOLUTION THEOEY 



of a higher order, for personal selection. It might seem perplexing 

 that processes of such importance should depend ultimately upon 

 chance ; but when we remember that there are only two directions of 

 variation, namely a plus direction or a minus direction, we recognize 

 that the chance of a majority in one direction or another is much 

 greater than that of absolute equilibrium between the two, and there 

 is therefore a very strong probability that in many individuals of the 

 vspecies either the upward or the downward movement of a determinant 

 A will preponderate. 



Now as such variation movements, when they are of a certain 

 strength, increase automatically, we can easily see that they must 

 gradually attain to a level at which they acquire selection value, and 

 how then, by personal selection, the ids with favourably varying 

 determinants may be collected together. 



Of course it is not possible to state positively the time at which 

 in individual cases a variation acquires a biological significance, that 

 is, selection value. We can only say in a general way that, as soon as it 

 attains this, personal selection either in a positive or a negative sense 

 Qiiust intervene ; an injurious variation tends to the elimination of its 

 possessor, a useful one increases the probability of its survival. 



There must, however, l)e for eveiy variation a stage of develop- 

 ment in which it has as yet no decisive biological importance, and this 

 stage need not by any means be so insignificant that we cannot see it, 

 or can hardly do so : in other words, there are characters which have 

 arisen through germinal selection, which are of purely ' morphological 

 importance.' 



It has often been disputed whether there can be any such thing 

 as 'purely morphological characters,' which are indifferent as far as 

 the existence of the species is concerned. This question used to be an 

 important one, because the sphere of operation, and therefore the 

 importance of the Darwin- Wallace selection — personal selection — 

 depends on the answer, since this mode of selection only begins when 

 a character has some biological importance. But as soon as we take 

 germinal selection into consideration the question loses its importance, 

 because we now know that every variation is indifferent to begin with, 

 but every one can, under favourable circumstances, be increased to such 

 a pitch that it attains biological importance, and that personal selection 

 then takes over the task of carrying it on, either in a positive or 

 a negative sense. We may therefore leave this disputed point alone 

 just now, for while germinal selection seems still far from being 

 generally recognized, we have to remember that we are not at all in 

 a position to judge with any certainty as to the biological value 



