DOMINATIONAL AND IMPREGNATIONAL INFLUENCES. 87 . 
overcome, and forestall rivals of the same species in taking possession 
of mates or of resources and in seizing on opportunities. The import- 
ance of conflict and rivalry between individuals of the same group in 
“ gaining possession of resources and mates was discussed in my paper 
on Intensive Segregation under the term that I nowuse. It has since 
then been discussed by Karl Pearson in his ‘‘Grammar of Science,”’ 
under the term ‘‘inter-group selection.’’ The chief objection to his 
term is that it ought naturally to include all the forms of what I have 
called ‘‘reflexive selection; but this is not in accordance with the 
definitions he has given. 
Dominational selection is due to inherited powers for overcoming 
rivals giving a larger share in propagation and survival through con- 
trol of resources and mates. 
Dominational election is due to acquired powers for overcoming 
rivals giving superior success and influence in the associating group. 
As prepotence is determined entirely by inherited powers, domina- 
tional election can have no influence on prepotence. Severe 
competition with domination is a condition that gives importance 
to isolation and partition, but these principles are not introduced 
without other causes, such as migration or transportation. 
6. The Forms of the Impregnational Method of Influence. 
Producing demarcation of racial Producing intensification of racial 
groups: groups: 
Impregnational isolation. Impregnational selection. 
Dimensional isolation. Dimensional interselection. 
Structural isolation. Structural interselection. 
Potential isolation. Potential selection. 
Segregate fecundity. Fecundal selection. 
Segregate vigor. 
Segregate adaptation. 
Segregate freedom from competition. 
Segregate escape from enemies. 
The impregnational method of influence is due to the need of coér- 
dination between the size, structure, sexual elements, and functions 
of each sex and the related characters of the other sex, in any inter- 
generating group, in order to secure a sufficient number of impreg- 
nated germs with the least expenditure and waste. Inasmuch as 
the influences shaping impregnation are inherited and not acquired, 
their chief effects are on racial rather than habitudinal groups. We 
therefore have no occasion to consider impregnational partition and 
election. 
Of the forms of impregnational isolation, the first five as given above 
were so fully considered in my paper on Divergent Evolution* that it 

* See Appendix I, where part of the paper is reproduced. 
