WCP4089

[1]

9. St. Mark's Crescent, N.W.¹

March 24th. 1869

Dear Darwin²

Allow me first to thank you for sending me a copy of the translation of Fritz Muller's³ interesting little work,⁴ which I have read with great pleasure; but whether it is owing to my extreme ignorance of aquatic animals, or to my having formed too high expectations of the book, it has given me the impression that the author has not made the most of his subject, & has not put either his facts or his arguments in the clear & powerful manner which you yourself would have done. If no one else makes a similar observation I must impute it to my own dulness in matters of minute anatomy & embryology.

[2] Many thanks for your corrections in my book.⁵ It only shows what absurd errors a person having once written may go over & over again & never see. As to Elk & Moose, I have always understood that they are the same animal, — the Americans improperly calling their Wapiti deer the Elk.⁶

I rather demur to the view that volcanoes are due to any general heaving up; and it seems to me that when a vent is once established the amount of pressure which would have caused a very slow upheaval of a wide district may be all expended in ejecting volcanic matter, and the downward pressure of adjacent districts may assist the ejecting process, & be rendered possible by the existence of the vent.⁷

I was sure that many naturalists would be disappointed at the scantiness of my notes on habits of animals &c. But the fact is my facts of this kind are very few, owing to my having devoted myself so [3] completely and almost exclusively to the work of collecting, — and I have no inclination whatever to write page after page, as some people can, of descriptions of animals & their habits, founded on very scanty observations.

As to the acquirement of plumage of Birds of Paradise perhaps I have been too hasty in assuming there is the kind of connection I have intimated as probable; yet I cannot help believing that it is true.⁸ My reasoning was somewhat as follows: in the process by which the male birds acquired their plumage, — colour would be first acquired, because variations in colour are most frequent & most extensive, — developments of special plumage in the head & tail next, — for the same reason, — & plumes of body, last. As all these modifications are very great in quantity there was probably a long period during [4] which the males differed from the females only in colour, — after that for another long period the long tail cirrhi were developed, — & then the body plumage would begin to be selected to give the last touch of improvement. The development of these different kinds of ornaments in these different parts of the body can not go on at once, but successively. The brilliant head & breast feathers, appeared after the first month when there was nothing else to appear, — when the long tail cirrhi became selected & developed they required another year's growth & nutriment, & were therefore obliged to follow ^after the colour of head &c. the growth of which was already established in the system, — so the side plumes, requiring another year[‘]s exclusive nutriment, could only follow after the already established tail cirrhi.

The same rule seems to follow in many other cases. The peacock takes three [5] years I am told to acquire his fully developed train, an unusual ornament, — the waxwing does not get the red tips to the secondaries till the 2nd. year & to the tertiaries still later. The Ruby hummer⁹ of N[orth]. America gets his gorget only the 2nd. year, — & Gosse says the Longtailed Jamaica hummer only gets the long feathers of the tail a year after he has got the otherwise perfect male plumage.¹⁰ As in all cases it seems to be the least common kind of ^sexual ornament that appears last, it appears a fair conclusion that those appear last which were selected last, & because they were selected last. I fear no cases of domesticated varieties will help us with facts, because sexual characters have never been selected to any ^thing like the enormous degree in which they occur in nature. [6] My statement about the male & female Cassowary sitting alternately was of course derived from the natives, as I never once even saw the adult birds myself.¹¹ I sh[oul]^d doubt the male's being less highly coloured, — as these birds have no enemies.

Male savages ornament themselves from personal vanity I sh[oul]^d. say, & partly no doubt with a view to admiration by the ladies.

You do not say how far you think my defence of the Dutch policy is successful.¹² That is a point on which I expect the most severe criticism, as it is a subject on which so much prejudice [7] exists in this country. As I went out with those prejudices, I ought to be at all events an impartial judge.

In my forthcoming article in the "Quarterly", I venture for the first time on some limitations to the power of natural selection.¹³ I am afraid that Huxley¹⁴ & perhaps yourself will think these weak & unphilosophical. I merely wish you to know that they are in no way put in to please the Quarterly readers, — you will [8] hardly suspect me of that, — but are the expression of a deep conviction founded on evidence which I have not alluded to in the article but which is to me absolutely unassailable.

With many thanks for your kind remarks on my book[.]

Believe me Dear Darwin| Yours very faithfully| Alfred R. Wallace [signature]¹⁵