From H. W. Bates 22 March 1865
Royal Geographical Society | 15, Whitehall Place, S.W.
March 22 1865
My dear Mr Darwin
It gave me great pleasure this morning to see a letter in your handwriting showing that you had recovered your previous tolerably good state of health.1 The news will be welcome to all our friends when I tell them.
Pray do not send your copy of the Heliconidæ paper as I have still a few left & will send one to Mr Walsh,2 to whom I am indebted for copies of his papers lately arrived. I have read every line of his with great pleasure,—just a little deadened perhaps by the diffuseness of his style & want of closeness in his otherwise just reasoning.
I will make use of this opportunity to tell you of a small discovery of mine lately made in working out the species of a very long genus of Longicorn Coleoptera. It is with regard to the abrupt & profound modifications in sexual parts between very closely-allied species. You will perhaps recollect my telling you some time ago of a series of dissections made by a friend of mine of the male organs in Chrysomelidæ he having found great differences from species to species & even separated what were previously considered to be varieties, on the ground of modifications in these organs.3 In my Longicorns the parts in question are the accessory organs, that is the terminal abdominal segment from which the organ protrudes when necessary. The genus is Colobothea—one of those genera of which so many exist in all orders, in which the species seem to have been endlessly multiplied by nature. Nearly all the species can be distinguished by the form of the acessory organs in the sexes & I have found most profound modifications in what would be otherwise considered as local varieties. I have no doubt whatever that the species on dissemination over a wide area & breaking up into local varieties undergo modifications of these organs very readily & that this fact has operated greatly in the multiplication of species in nature for it is difficult to conceive the variously formed males of these closely-allied races to be equally adapted to their own females & to the females of their sister races. There is a physical obstacle here in the way of amalgamation with the parent or sister forms of segregated local varieties or races. I shall publish my notes on the subject in the Annals & Mag. Nat. Hist. in the course of my papers on Amazons Longicornes.4
Yours sincerely | H W Bates
I am expecting “cartes” by every post from my photographer & will send a pair on their arrival5
Expresses pleasure at signs of CD’s recovery.
HWB’s work on the identification of species of the genus Colobthea; relates the large number of modifications that occur in the sexual organs of closely allied species. Does not doubt that this contributes greatly to multiplication of species in nature.
Please cite as
Darwin Correspondence Project, “Letter no. 4792,” accessed on 23 October 2016, http://www.darwinproject.ac.uk/DCP-LETT-4792