Thus the character of secondary sexual differences is determined by climate.) I am, therefore, fully prepared to admit the justness of your criticism on sexual selection of lepidoptera; but considering the display of their beauty, I am not yet inclined to think that I am altogether in error.
What you say about reversion (268/3.

For instance, the fact that reversion to the primary winter-form may be produced by the disturbing effect of high temperature (page 7).) being excited by various causes, agrees with what I concluded with respect to the remarkable effects of crossing two breeds: namely, that anything which disturbs the constitution leads to reversion, or, as I put the case under my hypothesis of pangenesis, gives a good chance of latent gemmules developing.

Your essay, in my opinion, is an admirable one, and I thank you for the interest which it has afforded me.
P.S.I find that there are several points, which I have forgotten.

Mr.
Jenner Weir has not published anything more about caterpillars, but I have written to him, asking him whether he has tried any more experiments, and will keep back this letter till I receive his answer.
Mr.Riley of the United States supports Mr.Weir, and you will find reference to him and other papers at page 426 of the new and much-corrected edition of my "Descent of Man." As I have a duplicate copy of Volume I.( I believe Volume II.

is not yet published in german) I send it to you by this post.