To Jeffries Wyman 3 December 
Down Bromley Kent
My dear Sir
I am very much obliged to you for your kindness in writing to me & for sending me the pamphlets.1 If you can at any time find out about the relative size of the eyes of the Cave Rat, it would be a very great favour.—2
You cannot tell how much your paper on Gestation has interested me.3 How facts do beat the wildest imagination! The case of the frogs has interested me particularly, because some time since I read up what I could find on subject, thinking it a good case against my notions, from absence of transitional states; but now your case is something on the road. But the unfortunate male fish with the load of eggs in their mouths exceeds everything;4 & what a curious fact about the foreign eggs in the mouths of some.5 It is quite a pity that there are not fish of the same group with cuckoo-like habits; your fact would so well have explained how the habit might have arisen.— Speaking of transitions Mr MacDonnell of Dublin writes to me that he has made some curious discoveries on the electrical organs of the Rays,6 being led thereto by trying to make the case of the Electrical organs, already so very difficult to me, still more unpleasant; but as I understand him his new facts help my views considerably.—
I am very glad to hear that you are collecting facts on the “Bull-dog” fish: I suppose & hope you will bring in about the Nˆata cattle.7 I am now at work in bringing out a Corrected Edition of the “Origin” & I will do myself the great pleasure of sending you a copy when it is published: I could not resist giving briefly your Hog case.8 By the way I have received another analogous fact in case of Horses.—9
I once saw several years ago Dr Ackland, & was charmed with him: I am pleased to hear that he defended me against so redoubtable an opposer as Agassiz.10 I was rather surprised that the latter did not attack me with more skill.—
Will you kindly forward the enclosed to Prof. Silliman by any opportunity: the note is merely to thank him for so kindly writing & giving me information.—11
Pray believe me, My dear Sir, with sincere thanks & respect | Yours very truly. | C. Darwin
If you ever write again to me, can you refer me to any paper on the Rattle of Rattle-snake; I want to see some account of the tip of tail in the young before the skin has ever been moulted; & the relation of the rattle in the old to the act of moulting. I want to see what relation there is to the tail 〈of〉 Trigonocephalus, the habits of which I mention in my Journal as Vibrating its tail.—12
"You cannot tell how much your paper on Gestation has interested me" ["On some unusual modes of gestation in batrachians and fishes", Am. J. Sci. 2d ser. 27 (1859): 5–13].
Robert McDonnell has made curious discoveries on electrical organs of rays.
Is giving JW’s hog case in corrected ed. [3d] of Origin.
Would like account of tip of tail of young rattlesnake.
Please cite as
Darwin Correspondence Project, “Letter no. 3005,” accessed on 27 March 2017, http://www.darwinproject.ac.uk/DCP-LETT-3005