ASA GRAY. 779 



correspoiKleucc dates iVoiii a letter oC J)ar\viii, written Ai)ril 25, ISo^, 

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

 How intimate and fVeqiKMit their e()rres|)oiidene,e became, and how 

 deeply each was interested in the work of the other is adiniral)ly shown in 

 the "Life and Letters of Charles Darwin." The i)ublished letters i)re- 

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

 equally simple, earnest, reiiuirkably free from prejudice, and anxious to 

 do justice to the work of others. Many of the problems upon wliich 

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

 and he w^as often able to aid Darwin by his observations, and still more 

 by his judicious and always accei)table criticisms. Wliile the naturalist 

 at Down was absorbed in the study 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 su(;h things 

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

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

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

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

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

 natural selection; aiul it was this letter, read at the Linnean 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 i)ri()rity 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, 1859, when lie presented his paper "On the 

 Botany of Japan" to this academy. He then stated that "the idea of 

 the descents of all similar or conspecific individuals from a common 

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

 tion, that it must needs be first tried uj)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 niore 

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

 written December 13, 1856, he had well expressed his own attitude by 

 saying, "I have as yet no opmion whatever, and no very strong biasJ^ 



