ions and comments display. What you say about
Prof. Cope's style has been often before said to me, and I have remarked
in his writings an unsatisfactory treatment of our common theory. This,
I think, perhaps is largely due to the complete absorption of his
mind in the contemplation of his subject: this seems to lead him to be
careless about the methods in which it may be best explained. He has,
however, a more extended knowledge than I have, and has in many ways a
more powerful grasp of the subject, and for that very reason, perhaps,
is liable to run into extremes. You ask about the skipping of the Zoea
stage in fresh-water decapods: is this an illustration of acceleration?
It most assuredly is, if acceleration means anything at all. Again,
another and more general illustration would be, if, among the marine
decapods, a series could be formed in which the Zoea stage became less
and less important in the development, and was relegated to younger and
younger stages of the development, and finally disappeared in those to
which you refer. This is the usual way in which the accelerated mode
of development manifests itself; though near the lowest or earliest
occurring species it is also to be looked for. Perhaps this to which
you allude is an illustration somewhat similar to the one which I have
spoken of in my series,

a--ab--abc--ae--------ad,

which like "a d" comes from the earliest of a series, though I should
think from the entire skipping of the Zoea stage that it must be, like
"a e," the result of a long line of ancestors. In fact, the essential
point of our theory is, that characteristics are ever inherited by the
young at earlier periods than they are assumed in due course of growth
by the parents, and that this must eventually lead to the extinction or
skipping of these characteristics altogether...

Such considerations as these and the fact that near the heads of series
or near the latest members of series, and not at the beginning, were
usually found the accelerated types, which skipped lower characteristics
and developed very suddenly to a higher and more complex standpoint in
structure, led both Cope and [myself] into what may be a great error. I
see that it has led you at least into the difficulty of which you very
rightly complain, and which, I am sorry to see, has cost you some
of your valuable time. We presumed that because characteristics were
perpetually inherited at earlier stages, that this very conce