To Francisco de Arruda Furtado   3 and 6 July 1881

Dear Sir

I thank you sincerely for your very kind & interesting letter of June 13^th. Absence from my home has caused me to delay in answering it.—¹ I consider it a fortunate event for science, that a man like yourself, who is not content merely to collect & describe species belonging to various neglected groups (though this is good & valuable work), but looks to philosophical questions, should inhabit a group of oceanic islands. You have a splendid field for observation, & I do not doubt but that your researches will be very valuable. I am too old to make any direct use of your observations, but this does not lessen my interest in them. It is no small satisfaction & reward to me to hear that my books have in part stimulated you in your Scientific work.— The case of the Vitrina is very curious: I remember reading that some Crustaceans on the shores of the U. States have been observed in a nearly similar condition.—² You ask me for suggestions, but I doubt whether I can send any which will not have occurred to you; but I will write down a few points, which if I were to reside for some years on your delightful islands, I should attend to.

1) If possible I would visit & collect on one or more of the most distant outlying islands & compare their plants & animals with those of the other islands. Indeed, after the case of the Galapagos Arch:, all the productions of all the islands ought to be carefully compared.³

(2) All the plants & animals from the highest mountain summits on all the islands ought to be collected.

3) It has been stated that on the N. shores of some of the N. islands, glacial deposits have been seen,—i.e. irregular beds with large, angular or rounded, perhaps scored stones, not of a volcanic nature.⁴

The size, shape, nature, & presence of fossil remains, in such stones should be carefully noted. This would be a most interesting subject for investigation, especially in relation to G. Distribution. It has, also, been stated (but I suppose erroneously) that a tooth of a Mastodon was formerly found in a small Tertiary formation on one of the islands.—⁵ Do you know Wallace’s works on Geographical Distribution?⁶ they w^d be worth your procuring.

(4) Is there any Light-house at the Azores: if so, land-birds would probably sometimes fly against the glass & be killed. In this case it w^d be adviseable to examine not only their feet & beaks for earth, but to dry the whole contents of their alimentary canals & place such contents on damp pure sand under a small bell-glass & see if any seeds were present which would germinate. If so to grow the plant & name it.

(5) Are trees with roots ever blown on shore? If so the roots should be split, & any earth between them, sh^d. be washed & placed on damp burnt earth or pure sand under a bell-glass, to see if such earth included any living seeds.

(6) After a heavy gale of wind in the direction of the prevailing currents it would perhaps be worth while to look to the rubbish cast up on the shore for seeds, insects &c.—

(7) I suppose that Lacerta inhabits the Azores, & if you could obtain their eggs, it would be worth while to try whether they w^d. float in sea-water & whether they will survive for 7 or 14 days immersion   The wide distribution of Lizards, land-mollusca & earth-worms is a most perplexing problem.—⁷

I fear that these suggestions will be of no use.— You have my hearty good wishes in your work. I honour you for working under the most difficult circumstances, namely with little sympathy from your neighbours.—

Believe me | Dear Sir, Yours faithfully | Charles Darwin

P.S. July 6^th— I have just returned home & have found there the essays which you have been so kind as to send me, & which I shall be very glad to read⁸