My life : a record of events and opinions - Wallace-online.org

LYELL AND DARWIN 227he usually did every year when he was wellenough,in order to see his friends and collect information forhis various works. On these occasions I usuallylunched with him and his brother, and sometimes oneother visitor, and had a little talk on some of thematters specially interesting him. He also sometimescalled on me in St. Mark's Crescent for a quiettalk or to see some of my collections.My first letter from him dealing with scientificmatters was in August, 1862, and our correspondencewas very extensive during the period occupied inwriting or correcting his earlier books on evolution,down to the publication of " The Expression of theEmotions in Man and Animals," in 1872, and afterwards,at longer intervals, to within less than a yearof his death. A considerable selection of our correspondencehas been published in the "Life andLetters" (1887), and especially in "More Letters"(1903) ;while several of the more interesting of thesewere contained in the one-volume life, entitled"Charles Darwin," which appeared in 1892. Asmany of my readers, however, may not have theseworks to refer to, I will here give a few of his lettersto myself which have not yet been published, andalso occasional extracts from some that have alreadyappeared, in order to make clear the nature of ourdiscussions.On February 23, 1867, he wrote to me asking ifI could solve a difificulty for him. He says :"OnMonday evening I called on Bates, and put a difficultybefore him which he could not answer, and, as onsome former similar occasion, his first suggestion was,*You had better ask Wallace.' My difficulty is, Whyare caterpillars sometimes so beautifully and artisticallycoloured ? Seeing that many are coloured to