Ɛpsilon

To Frederick Howlett   21 September [1878]

Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.

Sept. 21st

Dear Sir

I am sorry to say that I cannot throw a gleam of the obscurest light on your difficult problem, which has sometimes occurred to me as a most perplexing one.— But in fact we do not know enough of the meaning of the shape or size of the blood corpuscles or of scarcely any histological characters, for anyone to speculate on the subject.1

I shd. doubt about the peculiar shape of the corpuscles in the Camelidæ being due to inheritance from a remote progenitor; & most of the points which you specify as being alike in camels & ostriches could be accounted for, as it appears to me, more probably by adaption to similar conditions, rather than to inheritance from a, common ancestor, extremely remote in time.2

Thanking you for your very courteous expressions | I remain, Dear Sir | yours faithfully | Ch. Darwin

Postmark: SP 21 78

1
Howlett’s letter to CD has not been found. Howlett, a clergyman, was interested in microscopy.
2
The red blood cells of camelids and ostriches are oval; the shape is unusual for mammals, but not for birds (see Gulliver 1875).

Manuscript Alterations and Comments

1.4 characters,] after del ‘points’
2.2 inheritance from] interl
2.2 which] after del ‘in’
2.3 could] after del ‘both’
2.4 a] altered from ‘an’
2.4 common 2.5] interl

Please cite as “DCP-LETT-11701F,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-11701F