From A. Smither1   19 December 1872

2 Doughty St. W.C.

19 Decr 1872

Dear Sir

In reading your new book, an idea with regard to the erection of its feathers by a bird, & of its hair by a beast, has occurred to me, which I have thought I might dare to communicate to you.2 Please p⁠⟨⁠a⁠⟩⁠rdon me if m⁠⟨⁠y⁠⟩⁠ suggest⁠⟨⁠ion⁠⟩⁠ is [1 or 2 words illeg] It seems to me that this habit must be of real use for defence. Surely a hen with its feathers ruffled, (and its head drawn back to its body) is to a great extent defended against the attack of a dog.3 Similarly the bristling mane of a lion is a great protection against the teeth of an other animal. His enemy would hardly know ‘where to have him’, & would perhaps get merely a mouthful of hair ins⁠⟨⁠tea⁠⟩⁠d of a grip of the lion’s throat. Even in the case of the monkey & snake, the snake would have greater difficulty in fixing its fangs if the hair of the monkey were erected.4 This defence-theory seems to me so obvious, to have so strong a primâ facie probability on its side that I cannot but think that you have rejected it with very good reason for the expression-theory.5 I therefore beg again that you pardon me for troubling you with this letter.

Your obedt Servant | A. Smither

Chas Darwin. Esq. M.A. &c.

Smither has not been identified.
In Expression, pp. 95–104, CD had discussed the raising of hair and feathers.
In Expression, p. 97, CD had stated that ruffled feathers or raised neck-hackles in angry or frightened birds served no defensive function.
Smither refers to examples that CD used in Expression, pp. 96–7.
CD acknowledged that the erection of the dermal appendages such as hair or feathers did made an animal ‘appear larger and more frightful to its enemies or rivals’, but he doubted that the power of raising them was ‘primarily acquired for this special purpose’ (see Expression, p. 95). He argued that it was a reflex action produced by fear, which, through force of habit, could become a voluntary action for defensive purposes (ibid., pp. 101–2).

Please cite as “DCP-LETT-8686,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-8686