DIVERGENT EVOLUTION THROUGH SEGREGATION. 299 
the members of an inter-generaut, exclusive of their influence upon each 
other. The environment of an inter-generant includes members of the 
Same species only when these members are so near that they exert an 
influence through competition or otherwise, while at the same time they 
are so far differentiated that they do not inter-cross; in other words, the 
members of the same species can mutally belong to the environment 
only when they have acquired some of the characteristics of independ- 
ent species. The same environment extends as far as the activities 
that affect or may affect the species extend without undergoing change. 
Change in the environment is change in the external activities affect- 
ing the species. 
Entering a new environment is a change in the territorial distribution 
of the species, bringing either all or a portion of its members within 
the reach of new influences. This may also be called change of cnvi- 
ronment. 
Change in the organism, whether producing new adaptations to the 
environment or not, should be carefully distinguished from both of the 
above-described changes. 
Change of relations to the environment may be produced by change 
in the environment, or by entering a new environment, or by change 
in the organism. 
As great confusion has been occasioned by the terms * conditions of 
life,” and ‘‘ external conditions” being used, sometimes for activities 
outside of the species under consideration and sometimes for those 
within the species (as for example the influence upon the seed produced 
by its position in the capsule), [ have tried to avoid their use. 
Monotypic evolution is any transformation of a species that does not 
destroy its unity of type. 
Polytypie evolution or divergent evolution is any transformation of a 
species in which different types appear in different sections. 
CHAPTER I. 
THE EFFECTS OF SELECTION AND INDEPENDENT GENERATION CON- 
TRASTED. 
In as far as any theory of evolution fails of giving an explanation of 
divergence of character, in so far it fails of explaiming the origin of 
species. This is the crucial test which must decide the strength or 
weakness of every theory that is brought forward to account for the 
derivation of many species from one original species. A satisfactory 
theory will not only point out the conditions on which divergence 
depends, but will show that these conditions are the natural result of 
‘auses that are already recognized by science as having influence in 
the organic world, or that are now shown to have such influence. 
In the present chapter I shall present some reasons for believing 
that neither ‘natural selection,” nor “sexual selection,” nor ‘the 
