PREFACE TO THE SECOND EDITION. 



During the successive reprints of the first edition of this work, 

 published in 1871, I was able to introduce several Important cor- 

 rections; and now that more time has elapsed, I have endeavored 

 to profit by the fiery ordeal through which the book has passed, 

 and have taken advantage of all the criticisms which seem to me 

 sound. I ain also greatly Indebted to a large number of corre- 

 spondents for the communication of a surprising number of new 

 facts and remarks. These have been so numerous, that I have 

 been able to use only the more important ones; and of these, as 

 well as of the more important corrections, I will append a list. 

 Some new illustrations have been introduced, and four of the old 

 drawings have been replaced by better ones, done from life by 

 Mr. T. W. Wood. I must especially call attention to some observa- 

 tions which I owe to the kindness of Prof. Huxley (given as a sup- 

 plement at the end of Part I.), on the nature of the differences be- 

 tween the brains of man and the higher apes. I have been par- 

 ticularly glad to give these observations, because during the last 

 Sew years several memoirs on the subject have appeared on the 

 Continent, and their importance has been, in some cases, greatly 

 exaggerated' by popular writers. 



I may take this opportunity of remarking that my 

 critics frequently assume that I attribute all changes of 

 corporeal structure and mental power exclusively to the 

 natural selection of such variations as- are often called 

 spontaneous; whereas, even in the first edition of the 'Origin 

 of Species,' I distinctly stated that great weight must 

 be attributed to the inherited effects of use and disuse, with 

 respect both to the body and mind. I also attributed some amount 

 of modification to the direct and prolonged action of changed con- 

 ditions of life. Some allowance, too, must be made for occasional 

 reversions of structure; nor must we forget what I have called 

 "correlated" growth, meaning, thereby, that various parts of the 

 organization are in some unknown manner so connected, that 

 when one part varies, so do others; and if variations in the one 



