266 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 
of this germ cell would continue the struggle among determinants, and 
it would be expected that the strong determinant would continue to 
gain further advantage until the structure it represents reached its 
maximum efficiency. Similarly, a determinant that was for some 
reason deprived of its fair share of nutriment at any time would be 
weakened and would produce in cell division weakened daughter 
determinants. These in turn, unless especially favored, would wage 
a losing fight and continue to grow smaller and weaker. Each indi- 
vidual that might develop from such germ cells would have the charac- 
ters whose determinant had been weakened in a reduced and 
progressively degenerating condition. Finally, certain determinants 
might starve entirely, and the part for which they stood would dis- 
appear entirely from the ontogeny of the individual arising from these 
germ cells. 
In this way Weismann tried to explain the gradual dwindling 
and the final elimination of useless organs. So also he would explain 
definitely directed or orthogenetic variations, because germinal selec- 
tion, once started in a given direction, continues automatically till 
the goal of adaptiveness is reached. 
The most potent objections to the theory of germinal selection are 
as follows: 
1. There should be, according to this theory, certain pronounced 
tendencies in variability in definite directions, whereas fluctuating 
variations nearly always distribute themselves evenly about the mean 
or mode, and the same specific mean or mode is stationary in succes- 
sive generations. 
2. The theory implies too rapid and too general modification of 
parts and therefore does not accord with the fact that species are 
decidedly constant, except for occasional mutations, over long periods 
of time. To meet this objection Weismann proposes a new self- 
correcting mechanism that checks too rapid a development of char- 
acters. , 
3. The over- or undernourishment of determinants might con- 
ceivably induce size changes in characters already present; but could 
hardly be responsible for the origin of qualitatively different characters. 
4. Actual experiments in over- and underfeeding of animals have 
been carried on by certain experimenters in order to test out the theory 
of germinal selection. In the experiments of Kellogg, for example, 
involving feeding silkworm larvae only one-eighth of the normal 
amount of food, the only result was that the mature individuals were 
