The Descent of Man

the injurious will be thus eliminated. Uniformity
of character would, however, naturally follow
from the assumed uniformity of the exciting
causes, and likewise from the free intercrossing
of many individuals. During successive
periods, the same organism might in this
manner acquire successive modifications,
which would be transmitted in a nearly uniform
state as long as the exciting causes remained
the same and there was free intercrossing.
With respect to the exciting causes we can
only say, as when speaking of so-called spontaneous
variations, that they relate much more
closely to the constitution of the varying organism,
than to the nature of the conditions to
which it has been subjected.
CONCLUSION.
In this chapter we have seen that as man at the
present day is liable, like every other animal, to
multiform individual differences or slight va-