760 BIOGRAPHICAL MEMOIRS. 



taiu iuferences are slowly settling themselves in my mind or taking 

 shape; but on some of the most vexed questions, I have as yet no 

 opinion whatever, and no very strong bias^ thanks partly to the fact 

 that I can think of and investigate such matters only now and then, 

 and in a very desultory way." * 



In a letter of a year later, subsequent in date to Darwin's letter, 

 Gray wrote me with reference to my paper on " Species," read at the 

 meeting of the American Association in August, 1857, — which paper 

 may be taken, perhaps, as a culmination of the past, just as the new 

 future was to make its appearance, — pointing out to me the fatal objec- 

 tion to my argument. 



His words (dated November 7) are worth quoting : " Taking the 

 cue of species, if I may so say, from the inorgafiic, you develop the 

 subject to great advantage for your view, and all you say must have 

 great weight in 'reasoning from the general.' But in reasoning from 

 inorganic species to organic species, and in making it tell where you 

 want it, and /or ivhat you want it to tell, you must be sure that you are 

 using the word species in the same sense in the two; that the one is 

 really the equivalent of the other. TLiat is what I am not yet convinced 

 of; and so to me the argument comes only with the force of an analogy, 

 whereas I suppose you want it to come as demonstration. Very likely 

 you could convince me that there is no fallacy in reasoning from the one 

 to the other to the extent you do. But all my experience makes me 

 cautious and slow about building too much on analogies, and uutil 

 I see further and clearer I must continue to think there is an essential 

 dift'erence between kinds of animals or plants and kinds of matter. 



"How far we may safely reason from the one to the other is the 

 question. If we may do so even as far as you do, might not Agassiz (at 

 least plausibly) say that as the species Iron w^as created in a vast number 

 of individuals over the whole earth, so the presumption is that any 

 given species of plants or animals was originated in as many individuals 

 as there are now, and over as wide an area ; the human species under 

 as great diversities as it now has, barring historical intermixture; thus 

 reducing the question between you to iusigniflcauce? because, then, the 

 question whether men are of one or of several species would no longer 

 be a question, or of much consequence. You may answer him from 

 another starting point, no doubt ; but he may still insist that it is a 

 legitimate carrying out of your principle." 



In the same letter Gray prophesies as follows, from actual knowledge, 

 it now appears: "You may be sure that before long there must be 

 one more resurrection of the development theory in a new form, obviating 

 many of the arguments against it, and presenting a more respectable 

 and more formidable appearance than it ever has before." 



"Gray has some important observations on the bearing of hybridization on variation, 

 in a review of Hooker's Flora ludica in the nnmber of the Am. Jouraal of Science for 

 January, 1856, xxi, 134. 



