CHAPTER VI. DIFFICULTIES OF THE THEORY.
1. DIFFICULTIES OF THE THEORY OF DESCENT WITH MODIFICATION.
Long before the reader has arrived at this part of my work, a crowd of
difficulties will have occurred to him. Some of them are so serious that
to this day I can hardly reflect on them without being in some degree
staggered; but, to the best of my judgment, the greater number are only
apparent, and those that are real are not, I think, fatal to the theory.
These difficulties and objections may be classed under the following heads:
First, why, if species have descended from other species by fine
gradations, do we not everywhere see innumerable transitional forms? Why
is not all nature in confusion, instead of the species being, as we see
them, well defined?
Secondly, is it possible that an animal having, for instance, the structure
and habits of a bat, could have been formed by the modification of some
other animal with widely different habits and structure? Can we believe
that natural selection could produce, on the one hand, an organ of trifling
importance, such as the tail of a giraffe, which serves as a fly-flapper,
and, on the other hand, an organ so wonderful as the eye?
Thirdly, can instincts be acquired and modified through natural selection?
What shall we say to the instinct which leads the bee to make cells, and
which has practically anticipated the discoveries of profound
Fourthly, how can we account for species, when crossed, being sterile and
producing sterile offspring, whereas, when varieties are crossed, their
fertility is unimpaired?
The two first heads will be here discussed; some miscellaneous objections
in the following chapter; Instinct and Hybridism in the two succeeding