ASA GRAY. 779 



coiTespoiideucc daU'S from a letter of Darwin, written April 25, 1855, 

 asking" for information about the alpine plants of the United States. 

 How intimate and fre<pient their corresi)ondence became, and how 

 deepl^each was interested in the work of the other is admirably shown in 

 the "Life and Letters of Charles Darwin." The published letters pre- 

 sent a vivid picture of the inner scientific life of these two men, both 

 eqnally simple, earnest, remarkably free from prejudice, and anxious to 

 <lo justice to the work of others. Many of the problems upon which 

 Darwin was at work were those in which Gray was most interested; 

 and he was often able to aid Darwin by his observations, and still more 

 by his judicious and always acceptable criticisms. While the naturalist 

 at Down was absorbed in the stud^' of climbing plants and cross fertili- 

 zation, the greenhouses at Cambridge were also used as nurseries for 

 the growth of climbers and the odd, irregularly flowered plants which 

 ought to be cross-fertilized. The writer recalls the time when Dr. Gray 

 hardly ever passed in or out of the herbarium without stroking — patting 

 on the the back by way of encouraging them it almost seemed — the 

 tendrils of the climbers on the walls and porch; and when, on the an- 

 nouncement that a student had discovered another new case of cross- 

 fertilization in the garden, he would rush out bareheaded and breathless, 

 like a school-boy, to see the thing with his own critical eyes. 



Darwin, in a letter dated June 20, 1856, confided to Gray that he 

 had "come to the heterodox conclusion that there are no such things 

 as independently created species, — that species are only strongly de- 

 fined varieties." In this letter he also says: " I assume that species arise 

 like our domestic varieties with much extinction." About a year after 

 this (September 5, 1857) Darwin wrote to Gray the now famous letter, 

 in which be propounded the law of the evolution of species by means of 

 natural selection; and it was this letter, read at the Linuean Society 

 July 1, 1858, on the occasion of the presentation of the joint paper of 

 Darwin and Wallace "On the Tendency of Species to form Varieties; 

 and on the Perpetuation of Varieties and Species by Natural Means of 

 Selection," which fixed the date of the priority of the great discovery 

 as due to Darwin. What were Gray's own views on the subject of 

 evolution previous to the publication of the "Origin of Species," in 

 November, 1859, may perhaps be inferred from some remarks which he 

 made on January 11, 1850, when he presented his paper "On the 

 Botany of Japan" to this academy. Ue then stated that "tiie idea of 

 the descent of all similar or couspecific individuals from a common 

 stock is so natural, and so inevitably suggested by common observa- 

 tion, that it must needs be first tried ui)on the problem [of distribution], 

 and if the trial be satisfactory its adoption would follow as a matter of 

 course." In brief, he was inclined to accept evolution, but wished more 

 proof; and nearly three years earlier, in a letter to Professor Dana, 

 written December 13, 185G, he had well expressed his own attitude by 

 saying, "1 have as yet no opinion whatever, and no very strong bias.^^ 



