156 THE EVOLUTION THEORY 



cell lip to the whole would remain wliolly unexplained. The wliole 

 crop of spontaneous germ- variations, whenever it ceases to he 

 ' indifferent,' and becomes either ' good ' or ' bad,' comes under the 

 shears of personal selection and under its almost sovereign sway. 



On tlie other hand, the sudden first appearance of a saltatory 

 variation takes place quite independentl}^ of personal selection, 

 depending on similar variations in a number of ids, which remain 

 latent until they have by the process of reducing division wliich 

 precedes am^^himixis, chanced to attain a majority. In sudden bud- 

 variations we may perhaps suppose that reducing division occurring 

 in some still unverified abnormal manner is the reason whj' the 

 germinal variation suddenly makes itself visible — a supposition pre- 

 viously suggested as the explanation of the reversion of these sports. 



The rarity of bud- variation is thus explained, while the greater 

 frequency of saltatory variations in plants propagated by seed may 

 be accounted for by the regular occurrence of reducing division 

 in sexual reproduction. But that the same or similar variations 

 may occur in several, it may be in many, ids at the same time must 

 depend upon similar general influences which afiect the plant as 

 a whole, as happens through cultivation, manuring, and so on. I shall 

 return to this when discussincr the influence of the environment. 



In some quarters this whole conception of germinal selection has 



been characterized as the merest figment of imagination, condemned 



on this ground alone, that it is based on the differences in nutrition 



between such extremely minute quantities of substance as the 



chromosomes of nuclear sul)stance within the germ-cell. The quantity 



of suljstance is certainly minute, but it needs nutriment none the 



less, and can we believe that the stream of nourishment for all 



the invisibly minute vital elements is exactly alike? It may be 



admitted that the nourishment outside the ids is usuall}^ abundant, 



although undoubtedly fluctuations occur in it also, but it certainly 



does not follow from this that every vital unit within the id is 



similarly disposed in relation to the nutritive supply, or has food 



in equal quantities at its command, or even that each has as much 



as it can ever need. To make an assertion like this seems to me 



much the same as if an inhabitant of the moon, looking at this earth 



through an excellent telescope and clearly descrying the city of 



Berlin with its thronging crowds and its railways bringing in the 



necessaries of life from every side, should conclude from this abundant 



provision that the greatest superfluity prevailed within the town, 



and that every one of its inhabitants had as much to live upon 



as he couM possibly require. 



