756 BIOGRAPHICAL MEMOIRS. 



climate as to heat and dryness. The surprising revelations are now so 

 generally known that this brief reference to them is all that is here 

 needed. 



Gray's comprehensive knowledge of the plants of the world, of their 

 distribution, and specifically of the relations of North American species, 

 genera, and orders to those of the other continents, and the precision 

 of his knowledge, enabled him to be of much service to Darwin in the 

 preparation of the first edition of the Origin of Species, and afterward, 

 also, in the elaboration of Darwin's other publications. His mind was 

 not very strongly bound to opinions about species, partly because of 

 his natural openness to facts, his conclusions seeming always to have 

 only a reasonable prominence in his philosophical mind, rarely enough 

 to exclude the free entrance of the new, whatever the source, and to a 

 considerable extent from the difficulties he had experienced in defining 

 species and genera amidst the wide diversities and approximate blend- 

 lugs which variation had introduced. 



Darwin, in a letter to Gray written during the following summer,' 

 having in view Gray's article in this journal, and another discussion of 

 his — published in the proceedings of the American Academy, says, 

 "I declare that you know my book as well as I do myself, and bring to 

 the question new lines of illustration and argument in a manner which 

 excites my astonishment and almost my envy." "As Hooker lately said 

 in a note to me, you are, more than any one else, the thorough master 

 of the subject." 



Gray's "Darwiniana," published in 1870, is composed of a number of 

 his essays and reviews, from the American Journal of Science, the 

 "Nation" and the "Atlantic Monthly," together with a closing chapter, 

 written for the volume, entitled "Evolutionary Teleology." The last 

 chapter brings out Gray's adherence to the doctrine of natural selec- 

 tion, and also his divergence from true Darwinism. These divergences 

 are thus expressed : 



"We are more and more convinced that variation, and therefore the 

 ground of adaptation, is not a product of, but a response to, the action 

 of the environment. Variations, in other words the differences between 

 individual plants and animals, however originated, are evidently not 

 from without, but from within ; not physical, but physiological." And 

 elsewhere he has said that the variation in a species is apt to take place 

 in particular directions and make linear ranges of varieties, as often ex- 

 emplified among plants; which accords with the preceding conclusion, 

 pp. 386. 



Again speaking of the forms of Orchids and their connection with, 

 and relation to, insect fertilization, he says: "We really believe that 

 these exquisite adaptations have come to pass in the course of nature, 

 and under Natural Selection, but not that Natural Selection alone ex- 

 plains or in a just sense originates them. Or, rather, if this term is to 

 stand for sufficient cause and rational explanation, it must denote or in- 



