IX.] RETROGRESSIVE DEVELOPMENT IN NATURE, 1 5 



these persons are said to have uttered sounds resembHng the 

 cries of wild animals with which they had associated, but not 

 one was ever known to speak. When we consider the constant 

 and unremitting practice in speech which we gain in a life-time, 

 whether by speaking aloud or merely by thinking to ourselves, 

 and remember that in spite of the effect of this perpetual 

 exercise for centuries upon the human brain and vocal organs, 

 — the power of speech has not become in the slightest degree 

 fixed or intensified by heredity, I think that we are justified 

 by this one fact alone in altogether doubting whether acquired 

 characters can ever be transmitted in any real sense. Moreover 

 their transmission is quite incompatible with the only theory 

 of heredity which seems to me to be tenable. 



But if the results of the exercise of an organ are not inherited, 

 neither can the effects of disuse be handed down. Hence, if 

 this be true, the retrograde changes taking place during the 

 lives of individuals cannot possibly be intensified in the course 

 of generations ; for the process of retrogression would have to 

 begin afresh in each generation successively, and thus would 

 never advance any farther than it did in the individuals of the 

 first. We must, then, regard this supposition that degenera- 

 tion is caused by mere disuse as a mistaken one, and seek a 

 more satisfactory explanation of the facts. I think, moreover, 

 that such an explanation is to be found in what may be called 

 reversed natural selection. 



To state my meaning more clearly, Charles Darwin and 

 Alfred Russel Wallace have taught us to understand by 

 ' natural selection ' that process of elimination effected by 

 nature itself without the aid of man. Inasmuch as far more 

 individuals are born than can possibly live, only the best are 

 enabled to survive, the best being those which are so formed 

 as to be the 'fittest,' as we say, for the conditions of life in 

 which they are placed. As in each generation only the fittest 

 survive and propagate the species, their qualities only are 

 transmitted, while the less useful qualities of the weaker 

 individuals die out. Each successive generation will therefore 

 consist of individuals better organized than those of the pre- 

 ceding one, and thus useful characters will be gradually 

 intensified from generation to generation, until the greatest 

 possible degree of perfection is reached. Probably this theory 



