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Darwin Correspondence Project

From F. S. Arnold   [2]6 December 18781




I cannot see how the following passages ⁠⟨⁠w⁠⟩⁠hich appear in the Origin of Species on pages 86 & 89 respectively of the six⁠⟨⁠th⁠⟩⁠ Edition, can be reconciled.2

1 p. 86 And we have seen that it is the most closely allied forms— varieties of the same species, & species ⁠⟨⁠of the sa⁠⟩⁠me genus or of re⁠⟨⁠lat⁠⟩⁠ed genera,—which from having nearly the same structure, constitution & habits, gener⁠⟨⁠a⁠⟩⁠lly come into the severest competition with each other.3

2. p. 89. But it ⁠⟨⁠is seen⁠⟩⁠, that where they come into the ⁠⟨⁠clo⁠⟩⁠sest competition the advantages of diversification of the structure, with the accompanying differences of habit & consti⁠⟨⁠tution⁠⟩⁠ determine that the inhabitants, which thus jostle each other most closely, shall, as ⁠⟨⁠a⁠⟩⁠ general rule belong to what we ⁠⟨⁠ca⁠⟩⁠ll different genera & orders.

I suppose you have not time ⁠⟨⁠to⁠⟩⁠ reply to this.

Yrs. obediently | F. S. Arnold

C. D⁠⟨⁠arw⁠⟩⁠in Esqr. M.A.


The day is established by the relationship between this letter and the letter to F. S. Arnold, 31 December [1878]. Only the ‘6’ in the date is present in the original letter, which is torn.
In Origin 6th ed., p. 89, CD noted that in naturalised floras the number of new genera was proportionally much greater than the number of new species.


Origin 6th ed.: The origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. 6th edition, with additions and corrections. By Charles Darwin. London: John Murray. 1872.


Would like CD to explain how he reconciles two passages in 6th ed. of Origin.

Letter details

Letter no.
Francis Sorell Arnold
Charles Robert Darwin
Sent from
Source of text
DAR 159: 148
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 11775,” accessed on 27 October 2021,