I quite agree with what I gather to be your judgment, viz., that the direct action of the conditions of life on organisms, or the cause of their variability, is the most important of all subjects for the future. For some few years I have been thinking of commencing a set of experiments on plants, for they almost invariably vary when cultivated. I fancy that I see my way with the aid of continued self-fertilisation. But I am too old, and have not strength enough. Nevertheless the hope occasionally revives.
Finally let me thank you for the very kind manner in which you often refer to my works, and for the even still kinder manner in which you disagree with me.
With cordial thanks for the pleasure and instruction which I have derived from your book, etc.
LETTER 304. TO COUNT SAPORTA. Down, February 13th, 1881.
I received a week or two ago the work which you and Prof. Marion have been so kind as to send me. (304/1. Probably "L'Evolution du Regne vegetal," I. "Cryptogames," Saporta & Marion, Paris, 1881.) When it arrived I was much engaged, and this must be my excuse for not having sooner thanked you for it, and it will likewise account for my having as yet read only the preface.
But I now look forward with great pleasure to reading the whole immediately. If I then have any remarks worth sending, which is not very probable, I will write again. I am greatly pleased to see how boldly you express your belief in evolution, in the preface. I have sometimes thought that some of your countrymen have been a little timid in publishing their belief on this head, and have thus failed in aiding a good cause.
LETTER 305. TO R.G. WHITEMAN. Down, May 5th, 1881.
In the first edition of the "Origin," after the sentence ending with the words "...insects in the water," I added the following sentence:—
"Even in so extreme a case as this, if the supply of insects were constant, and if better adapted competitors did not already exist in the country, I can see no difficulty in a race of bears being rendered by Natural Selection more and more aquatic in their structures and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale." (305/1. See Letters 110 and 120.)
This sentence was omitted in the subsequent editions, owing to the advice of Prof. Owen, as it was liable to be misinterpreted; but I have always regretted that I followed this advice, for I still think the view quite reasonable.