It would save you trouble to forward this with my kindest remembrances to Falconer.
(176/1. The following letter was the beginning of a correspondence with Mr. B.D. Walsh, whom C.V. Riley describes as "one of the ablest and most thorough entomologists of our time.")
LETTER 176. B.D. WALSH TO CHARLES DARWIN. Rock Island, Illinois, U.S., April 29th, 1864.
(176/2. The words in square brackets are restorations of parts torn off the original letter.)
More than thirty years ago I was introduced to you at your rooms in Christ's College by A.W. Grisebach, and had the pleasure of seeing your noble collection of British Coleoptera. Some years afterwards I became a Fellow of Trinity, and finally gave up my Fellowship rather than go into Orders, and came to this country. For the last five or six years I have been paying considerable attention to the insect fauna of the U.S., some of the fruits of which you will see in the enclosed pamphlets. Allow me to take this opportunity of thanking you for the publication of your "Origin of Species," which I read three years ago by the advice of a botanical friend, though I had a strong prejudice against what I supposed then to be your views. The first perusal staggered me, the second convinced me, and the oftener I read it the more convinced I am of the general soundness of your theory.
As you have called upon naturalists that believe in your views to give public testimony of their convictions, I have directed your attention on the outside of one or two of my pamphlets to the particular passages in which [I] have done so. You will please accept these papers from me in token of my respect and admiration.
As you may see from the latest of these papers, I [have] recently made the remarkable discover that there [are the] so-called "three sexes" not only in social insects but [also in the] strictly solitary genus Cynips.
When is your great work to make its appearance? [I should be] much pleased to receive a few lines from you.
LETTER 177. TO B.D. WALSH. Down, October 21st [1864].
Ill-health has prevented me from sooner thanking you for your very kind letter and several memoirs.
I have been very much pleased to see how boldly and clearly you speak out on the modification of species. I thank you for giving me the pages of reference; but they were superfluous, for I found so many original and profound remarks that I have carefully looked through all the papers. I hope that your discovery about the Cynips (177/1. "On Dimorphism in the hymenopterous genus Cynips," "Proc. Entom. Soc. Philadelphia," March, 1864. Mr. Walsh's view is that Cynips quercus aciculata is a dimorphous form of Cynips q. spongifica, and occurs only as a female. Cynips q. spongifica also produces spongifica females and males from other galls at a different time of year.) will hold good, for it is a remarkable one, and I for one have often marvelled what could be the meaning of the case. I will lend your paper to my neighbour Mr. Lubbock, who I know is much interested in the subject. Incidentally I shall profit by your remarks on galls. If you have time I think a rather hopeless experiment would be worth trying; anyhow, I should have tried it had my health permitted. It is to insert a minute grain of some organic substance, together with the poison from bees, sand-wasps, ichneumons, adders, and even alkaloid poisons into the tissues of fitting plants for the chance of monstrous growths being produced. (177/2. See "Life and Letters," III., page 346, for an account of experiments attempted in this direction by Mr. Darwin in 1880. On the effects of injuring plant-tissues, see Massart, "La Cicatrisation, etc." in Tome LVII. of the "Memoires Couronnes" of the Brussels Academy.)
My health has long been poor, and I have lately suffered from a long illness which has interrupted all work, but I am now recommencing a volume in connection with the "Origin."
P.S.--If you write again I should very much like to hear what your life in your new country is.