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Darwin Correspondence Project

To J. S. Henslow   [24 January 1840]

Friday Morning

My dear Henslow

I have just received your letter. as the waggon goes tomorrow, I pack up the specimens at once.— I believe you may keep them all.— They all come from the Maldeeve & Chagos lagoon-islands or atolls in the Indian Ocean,—islands precisely like Keeling Island.—

I hope they may be of any use to you.—

I send a couple copy of abstract of my worm Paper useless to me.—

Of course you have thought of Drummonds light.—1 Also of the use put to burn coral, shells, & limestone in the East Indian Archipelago to give a relish to the chewing of Betel.— In S. America, I believe potash is used, in analogous manner in chewing the Cocos leaves—2

I am in a hurry so goods Bye | C. Darwin

Do you recollect our discussion about varieties of same plants not having three primary—3 Surely I have seen pale yellow hyacinth, & certainly blue & pink ones.— pray tell me is it not so.—


‘Drummond light. The lime-light, or oxy-hydrogen light (invented by Capt. T. Drummond, R.E., c 1825), wherein a blow-pipe flame … impinges on a piece of pure lime, and renders it incandescent.’ (OED).
Coca leaves, chewed by South American Indians, contain various alkaloids, including cocaine. In Peru the Indians add unslaked lime or a preparation made from the ashes of the quinoa plant (EB, article on ‘Coca’).
Primary colours. CD was questioning a generalisation Henslow had made in Henslow 1837b, p. 201. Other conversations with Henslow on empirical laws of variation are recorded in CD’s transmutation notes, e.g., Notebook C: 192.


Sends specimens from Indian Ocean atolls.

Letter details

Letter no.
Charles Robert Darwin
John Stevens Henslow
Sent from
London, Upper Gower St, 12
Source of text
DAR 93: A3–4
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 552,” accessed on 16 June 2019,

Also published in The Correspondence of Charles Darwin, vol. 2