378 Ewart— Variation: Germinal and Environmental. 
claw and the faint arching of the tail may be held as indicating that the units of 
germ-plasm contributed by the male white fantail sire contested every inch of 
ground throughout the whole period of development, and that, when a small point 
is gained, it may be held to the last. Even in inbred stock, reversion occasionally 
occurs. Further experiments may show that the slight reversions familiar to 
breeders are due to loss of vigour in one or both of the parents. 
Recently acquired characters are the first to go, not, I think, because the vital 
units representing them are few in number, but because they are wanting in vigour 
or something akin to vigour. Hence, when the stress comes they deteriorate and 
ultimately count for little or nothing, with the result that the new individual is 
launched into the world minus the decorations and other traits that characterized 
the variety or race to which it by birth belongs. 
