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Darwin Correspondence Project

From Francis Galton   4 June 1872

42 Rutland Gate SW

June 4/72

My dear Darwin

Thank you very much about the rabbits— I however sincerely trust you did not send your man all the way on purpose for them alone!1 Any how I feel I have put you to much trouble and can only repeat how greatly I am obliged.

Your criticisms on my paper are very gratifying to me the more so that the question you put, is one to which I can at once reply.2

You ask, why hybrids of the first generation are nearly uniform in character while great diversity appears in the grand children & succeeding generations?

I answer, that the diagram shews (see next page) that only 4 stages separate the children from the parents but 20 from their grand-parents and therefore judging from these limited data alone, (ignoring for the moment, all considerations of unequal variability in the different stages & of pre-potence of particular qualities, &c—) the increase of the mean deviation of the several grandchildren (from the average hybrid) over that of the several children is as /20:/4 or more than twice as great. The omitted considerations would make the deviation (as I am prepared to argue) still greater.3

[DIAG HERE]

I will add the explanatory foot-note you most justly suggest,4 & should be very glad if you wd. let me have your copy back (I will return it) with marks to the obscure passages that I may try to amend them.

I found the 〈    〉 an uncommonly tough 〈job〉;—having to avoid hypothesis on the one hand & truism on the other and, again, the difficulty of being sufficiently general & yet not too vague.

It is very difficult to draw a correct verbal picture in mezzo tint, I mean by burnishing out the broad effects and not by drawing hard outlines.

Ever very sincerely | Francis Galton

I have knocked every symbol out of my paper & wholly rearranged the diagrams &c to make it less unintelligible.—5

FG

A pleasant journey & rest, to you all!6

Footnotes

Galton had offered to send CD a copy of a paper on blood-relationship that he was preparing for a meeting of the Royal Society (Galton 1872a; see letter from Francis Galton, 28 May 1872). The paper was read on 13 June 1872. CD’s comments have not been found.
Galton marked different elements of his diagram in red and blue crayon; elements marked in red are reproduced here in bold type, and elements marked in blue are reproduced in italic type.
There are no footnotes in the published paper (Galton 1872a).
See Galton 1872a, pp. 398 and 399.
The Darwins went to stay with William Erasmus Darwin in Southampton from 8 to 20 June 1872 (Emma Darwin’s diary (DAR 242)).

Summary

Thanks CD for criticisms of his paper; explains why there is greater diversity among succeeding generations than in the first.

Letter details

Letter no.
DCP-LETT-8368
From
Francis Galton
To
Charles Robert Darwin
Sent from
London, Rutland Gate, 42
Source of text
DAR 105: A61–3
Physical description
5pp

Please cite as

Darwin Correspondence Project, “Letter no. 8368,” accessed on 18 September 2019, https://www.darwinproject.ac.uk/letter/DCP-LETT-8368.xml

Also published in The Correspondence of Charles Darwin, vol. 20

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