i867.] SEXUAL SELECTION. 277 



do you happen to know by any odd chance a very good- 

 natured and acute observer in the Malay Archipelago, who 

 you think would make a few easy observations for me on the 

 expression of the Malays when excited by various emotions ? 

 For in this case I would send to such person a list of queries. 

 I thank you for your most interesting letter, and remain, 



Yours very sincerely, 



Ch. Darwin. 



C. Darwin to A. R. Wallace. 



Down, March [1867]. 



My dear Wallace, — I thank you much for your two 

 notes. The case of Julia Pastrana* is a splendid addition to 

 my other cases of correlated teeth and hair, and I will add it 

 in correcting the press of my present volume. Pray let me 

 hear in the course of the summer if you get any evidence 

 about the gaudy caterpillars. I should much like to give 

 (or quote if published) this idea of yours, if in any v/ay sup- 

 ported, as suggested by you. It will, however, be a long 

 time hence, for I can see that sexual selection is growing 

 into quite a large subject, which I shall introduce into my 

 essay on Man, supposing that I ever publish it. I had 

 intended giving a chapter on man, inasmuch as many call 

 him (not quite truly) an eminently domesticated animal, but 

 I found the subject too large for a chapter. Nor shall I be 

 capable of treating the subject well, and my sole reason for 

 taking it up is, that I am pretty well convinced that sexual 

 selection has played an important part in the formation of 

 races, and sexual selection has always been a subject which 

 has interested me much. I have been very glad to see your 

 impression from memory on the expression of Malays. I 

 fully agree with you that the subject is in no way an im- 

 portant one ; it is simply a " hobby-horse " with me, about 

 twenty-seven years old ; and after thinking that I would write 



* A bearded woman having an irregular double set of teeth. ' Animals 

 and Plants,' vol. ii. p. 328. 



