FIFTY YEARS OF DARWINISM 51 



The analogy seems to me far looser between the 

 changes of configuration of matter witnessed by 

 the physicist and the modification of a species as 

 a result of the struggle with its organic environ- 

 ment. The essential characteristics by which the 

 evolutionary history of the organic world di- 

 verges widely from that of the inorganic is very 

 clearly stated in the following brief passage from 

 a letter^ written by Charles Darwin to Sir Jo- 

 seph Hooker, on November 23, 1856, just three 

 years before the publication of the Origin: — 



" Again, the slight differences selected, by which a 

 race or species is at last formed, stands, as I think can 

 be shown (even with plants, and obviously with animals), 

 in a far more important relation to its associates than 

 to external conditions. Therefore, according to my 

 principles, whether right or wrong, I can not agree 

 with your proposition that time, and altered conditions, 

 and altered associates, are ' convertible terms.' I look 

 at the first and last as far more important, time being 

 important only so far as giving scope to selection." 



THE FIFTIETH ANNIVERSARY OF THE ORIGIN 

 OF SPECIES;— A RETROSPECT 



That the Origin of Species, which Darwin de- 

 scribed as undoubtedly the chief work of his life," 

 should have been bitterly attacked and misrepre- 

 sented in the early years of the last half century, 

 is quite intelligible; but it is difficult to under- 

 stand the position of a recent writer who main- 

 tains that the book exercised a malignant influ- 



' Life and Letters, II, p. 87. 

 ' Life and Letters, I, p. 86. 



