'MUTATION' EEJECTED BY DAKWIN 43 



descent with modification of species, by no means 

 implying change by large and sudden steps as 

 in the usual modern acceptation of the term. 

 Indeed, the words * mutable ', ' mutability ', and 

 their opposites, have never been employed with 

 the special significance now attached to 'muta- 

 tion '. Every one believes in the mutability of 

 species, but opinions diifer as to whether they 

 change by mutation. 



It is a mistake to suppose that Darwin did 

 not long and carefully consider large variations, 

 or 'mutations', as supplying the material for 

 evolution. Writing to Asa Gray as early as 

 August 11, 1860, he said of great and sudden 

 variation : 



' I have, of course, no objection to this, indeed it would be 

 a great aid, but I did not allude to the subject, for, after 

 much labour, I could find nothing which satisfied me of the 

 probability of such occurrences. There seems to me in 

 almost every case too much, too complex, and too beautiful 

 adaptation, in every structure to believe in its sudden pro- 

 duction.' 1 



In the twenty years between 1860 and 1880 we 

 find that Darwin was continually brought back to 

 this subject by his correspondents, and by reviews 

 and criticisms of his works. Scattered over this 

 period we find numbers of letters in which he 

 expressed his disbelief in an evolution founded 



my way to arrive at any better terms. It will be years before 

 I publish, so that I shall have plenty of time to think of better 

 words. Development would perhaps do, only it is applied to the 

 changes of an individual during its growth.' More Letters, i. 50. 

 See also p. 22 . 1. * Life and Letters, ii. 333. 



