36 GERMINAL SELECTION. 



The first and most natural explanation will be this 

 that through selection the zero-point, about which, 

 figuratively speaking, the organ may be said to oscil- 

 late in its plus and minus variations, is displaced up- 

 wards or downwards. Darwin himself assumed that 

 the variations oscillated about a mean point, and the 

 statistical researches of Galton, Weldon, and others 

 have furnished a proof of the assumption. If selec- 

 tion, now, always picks out the plus variations for 

 imitation, perforce, then, the mean or zero-point will be 

 displaced in the upward direction, and the variations 

 of the following generation will oscillate about a 

 higher mean than before. This elevation of the zero- 

 point of a variation would be continued in this manner 

 until the total equilibrium of the organism was in 

 danger of being disturbed. 



There is involved here, however, an assumption 

 which is by no means self-evident, that every advance- 

 ment gained by the variation in question constitutes 

 a new centre for the variations occurring in the fol- 

 lowing generation. That this is a fact, is proved by 

 such actual results of selection as are obtained in the 

 case of the Japanese cock. But the question remains, 

 Why is this the fact? 



Now here, I think, my theory of determinants gives 

 a satisfactory answer. According to that theory every 

 independently and hereditarily variable part is repre- 

 sented in the germ by a determinant, that is by a de- 

 terminative group of vital units, whose size and power 

 of assimilation correspond to the size and vigor of the 

 part. These determinants multiply, as do all vital 

 units, by growth and division, and necessarily they in- 

 crease rapidly in every individual, and the more 

 rapidly the greater the quantity of the germinal cells 



