SELECTED ADAPTATIONS 449 
offspring, and the more often such peculiarities have appeared 
in the line of ancestry the surer they are to reappear in all 
the descendants. Neo-Darwinism is thus in sharpest contrast 
with Neo-Lamarckism. The thoroughgoing Darwinian of 
to-day rejects all direct influence of the environment as a 
factor in organic evolution. Assume spontaneous variations, 
he would say, and let some of them be in adaptational direc- 
tions, then in the struggle for existence which is always going 
on, the life and death of rivals will turn upon which has in- 
herited the better equipment, and upon this will also depend 
the chance of transmitting to offspring the qualities which 
saved the parent’s life. Every gain in efficiency of adaptation 
will thus be preserved and successive gains accumulated till 
highest efficiency is reached, and when the most perfect 
adaptation has been secured it will be maintained indefinitely 
so long as the environment remains essentially unchanged. 
Since there are often different ways of attaining the same 
end, and so fitting different individuals successfully into the 
same environment, and since also there are different environ- 
ments to which a variable species may accommodate itself, 
such a species may give rise to several species in the course 
of many generations. If the intermediate forms or “‘connect- 
ing links” from being less perfectly adapted than the extreme 
forms should eventually succumb in the struggle, and so 
become extinct branches of the genealogical tree, gaps would 
appear between the surviving forms permitting us to define 
them as distinct species. A longer continuation of the same 
process would result in the differentiation of genera, families, 
and higher groups. 
Let us see how the theory of natural selection would apply 
to our supposed evolution of clematis. Imagine many 
thousand primitive marsh-marigold individuals inhabiting 
moist localities surrounded by drier spaces. These plants 
would be sure to vary somewhat in their ability to withstand 
_occasional dry seasons. Among the millions of seeds pro- 
duced by the tougher individuals a good share would surely 
be scattered along the edge of the drier spaces where there 
would yet be enough moisture for them to sprout. Those of 
the seedlings which had come from the toughest parents and 
