To H. G. Bronn 5 October 
Down Bromley Kent [Eastbourne]
Dear & much respected Sir
I ought to apologise for troubling you; but I have at last carefully read your excellent criticisms on my Book.—1 I agree with much of them, & wholly with your final sentence.2 The objections & difficulties, which may be urged against my view, are indeed heavy enough almost to break my back; but it is not yet broken! You put very well & very fairly that I can in no one instance explain the course of modification in any particular instance. I could make some sort of answer to your case of the two Rats;3 & might I not turn round, & ask him, who believes in the separate creation of each species, why one Rat has a longer tail or shorter ears than another? I presume that most people would say that these characters were of some use or stood in some connection with other parts; & if so, natural selection could act on them. But as you put the case, it tells well against me. You argue most justly against my question, whether the many species were created as eggs or as mature &c;4 I certainly had no right to ask that question.—
I fully agree that there might have been as well 100,000 creations as 8 or 10, or only one. But then on the view of 8 or 10 creations, (i.e. as many as there are distinct types of structure) we can on my view understand the homological & embryological resemblances of all the organisms of each type; & on this ground almost alone I disbelieve in the innumerable acts of creation.— There are only two points on which, I think, you have misunderstood me: I refer only to one Glacial period as affecting the distribution of organic beings: I did not wish even to allude to the doubtful evidence of Glacial action in the Permian & Carboniferous periods.5 Secondly, I do not believe that the process of development has always been carried on at the same rate in all different parts of the world.6 Australia is opposed to such belief.— The nearly contemporaneous equal development in past periods I attribute to the slow migration of the higher & more dominant forms over the whole world; & not to independent acts of development in different parts.— Lastly, permit me to add that I cannot see the force of your objection, that nothing is effected until the origin of life is explained:7 surely it is worth while to attempt to follow out the action of Electricity, though we know not what electricity is.
If you should at any time do me the favour of writing to me, I should be very much obliged if you would inform me, whether you have yourself examined Brehm’s sub-species of Birds;8 for I have looked through some of his writings, but have never met an Ornithologist who believed in his w〈orks.〉 Are these sub-species really characteristic of certain different regions of Germany?
Should you write, I should much like to hear how the German Edition sells.—
With my once more sincerely expressed gratitude & with entire respect | I beg leave to remain | Dear & Honoured Sir | Yours sincerely & respectfully | Charles Darwin
Bronn’s Criticisms for New Edit of Origin.
Objects that I cannot precisely say why *two species of Rats [interl] Hare & rabbit assumed by selection their several [interl] present characters— very true I can in no case say this— we know so little of use of parts & laws of correlation.— *But I confess, I thus evade every special difficulty. Why one gets round & another pointed leaves. [added]
Objects that in case of two varieties still living in abundance side by side how can intermediate vars *have been exterminated [above del ‘be living’]— But are there such cases, excluding such vars. as albinoe.— Do not they inhabit distinct countries or stations— surely this is the general rule.—
Do you believe in Brehms sub-species. Have you seen them?10
Thinks that varieties arising from external conditions are linked together by intermediates—not those produced by n. selection.—
Why of two cells, primordial, one got volition & sensation & one did not.—
Says I ought to answer [o' del] whether my primordial forms were created as eggs or full-grown &c.— Admits that vegetable-cell wd. come first.
I think Schiodte says the eyes not so completely gone, at least from more related to those of external world [n‘ del] near entrance of cave—11 [ave-Rat regained some sight’ del]12
I shd never suppose with respect to his supposed changes in 2 Rats, that first longer or shorter tail & larger [interl] ears were acquired, but that all were modified together.—
*Might I not ask Creationist why tail longer or ear shorter? I could not ask this of him who believes that God makes his creation different for mere variety—like man fashions a pattern for mere variety. [added pencil]
Objects there might <have be>en 100,000 creations as well as one; I agre<e, b>ut then these would not have borne signs of common descent in homologies & embryology & rudimentary organs.
Some mistake about my supposing several glacial periods— Permian & Chalk.—
“Why shd the process of development have always carried on same rate in all different parts of world?” I do not believe so— N. Zealand & Australia.
** I cannot see force of your objection because one cannot explain origination of life— **the far grandest problem of any [interl] why it wd not be gain to explain or account for forms; if this could be done — so we [o` del] do not know what electricity is, but we trace its action.— [del pencil]
I fully agree to your final sentence—& I fully admit the many awful difficulties in my view.
Certainly, as he grants < > that both yet descended from one common parent.
As I cannot justify my opinions in any one single case, so I need not in any.—is as [over ‘very’] true *as it is [above del ‘& very’] severe.—
Though I can in no single instance, (except by conjecture, as longer legs of Hare for fleetness & not for [form]—longer ears to hear with) explain changes [ith' del] yet the structure &c led me to conclusion.— Laws of Variation will hereafter be made out far clearer.
Answers HGB’s criticism of Origin.
Explains HGB’s case of differences in rats by adaptation.
CD’s view explains homological and embryological resemblances of each type.
Does not believe all development is at same rate. Cites Australian forms.
Does not see force of objection that origin of life must be explained.
Asks if C. L. Brehm’s subspecies of birds are really characteristic of regions of Germany.
Please cite as
Darwin Correspondence Project, “Letter no. 2940,” accessed on 24 August 2016, http://www.darwinproject.ac.uk/DCP-LETT-2940