Alfred Russel Wallace 



giving a grand paper (as I infer from remarks in discus- 

 sion) on Geographical Distribution. 



I am very weak, so will say no more. — Yours very sin- 



c^^^l^' C. Darwin. 



In Vol. I., p. 93, of the '' Life and Letters of Charles 

 Darwin/' Darwin states the circumstances which led to 

 his writing the '^ Descent of Man.'' He says that his 

 collection of facts, begun in 1837 or 1838, was continued 

 for many years without any definite idea of publishing on 

 the subject. The letter to Wallace of May 28, 1864, in reply 

 to the latter's of May 10, shows that in the period of ill- 

 health and depression about 1864 he despaired of ever being 

 able to do so. 



5 Westhourne Grove Terrace, W, May 10, 1864. 



My dear Darwin, — I was very much gratified to hear by 

 your letter of a month back that you were a little better, 

 and I have since heard occasionally through Huxley and 

 Lubbock that you are not worse. I sincerely hope the sum- 

 mer weather and repose may do you real good. 



The Borneo Cave exploration is to go on at present with- 

 out a subscription. The new British consul who is going out 

 to Sarawak this month will undertake to explore some of the 

 caves nearest the town, and if anything of interest is obtained 

 a good large sum can no doubt be raised for a thorough ex- 

 ploration of the whole country. Sir J. Brooke will give every 

 assistance, and will supply men for the preliminary work. 



I send you now my little contribution to the theory of 

 the origin of man. I hope you will be able to agree with 

 me. If you are able, I shall be glad to have your criticisms. 



I was led to the subject by the necessity of explaining 

 the vast mental and cranial differences between man and 

 the apes combined with such small structural differences 

 in other parts of the body, and also by an endeavour to 

 account for the diversity of human races combined with 



152 



