240 DAR WIN. 



that single variations are of even less importance, 

 in comparison with individual differences, than I 

 formerly thought." He here refers to the aggre- 

 o^ate of distinction between two forms. 



This reaction was accompanied by a slow change 

 of mind towards the Lamarckian factor of the 

 inheritance of the effects of use and disuse. This 

 was brought about, apparently, not through a re- 

 newed study of the Philosophie Zoologique, but by 

 Darwin's own observations upon the domesticated 

 animals, especially in his records of structures 

 which were developing and degenerating entirely 

 apart from the main course of the artificial selec- 

 tion of breeders, as well as from the weight of 

 utility or usefulness in the scale of survival in 

 Nature. He may have been influenced also by the 

 thorough Lamarckism of Herbert Spencer, although 

 this does not appear in the Life and Letters. 



Darwin's gradual recession from his exclusion 

 of the Buffon- St. Hilaire factor also evidently 

 began in course v of the preparation of his great 

 work upon ' Variation.' He was influenced by his 

 own wider range of observation, and, later, by the 

 observations of Wagner, of Allen, and others. As 

 early as 1862 he wrote to Lyell {Life and Letters, 

 Vol. n., p. 390): — 



" I hardly know why I am a little sorry, but my present work is 

 leading me to believe rather more in the direct action of physical 

 conditions. I presume I regret it, because it lessens the glory of 

 Natural Selection, and is so confoundedly doubtful. Perhaps I 



