ORGANIC EYOLUTIOX — MENTAL 175 



by the lapsing of ancestral inborn variations, and man 

 would decrenerate towards that ancestral form in which 

 it did not exist. 



Now of all the traits acquirable by man, articulate 

 language is the most difficult to acquire. It is certain 

 that it can only have been perfected by slow improve- 

 ments occupying long ages, during which also occurred 

 a corresponding and contemporaneous evolution of the 

 structures which subserve speech and thought. If, then, 

 the knowledq;e of articulate language were lost and man 

 survived, before it could be re-invented and perfected, the 

 structures which subserve it (tongue, brain, &c.) would 

 probably have retrogressed so far, that the acquirement 

 of articulate language, in any form approaching perfec- 

 tion, would be impossible, until, by a slow process of 

 evolution, man had once more emerged from the brute. 



The slow evolution of speech, and the slow concurrent 

 evolution of the structures which subserve speech, dur- 

 ing innumerable generations, the one generation trans- 

 mitting that which it acquired from the preceding- 

 generation, with slight improvements, to succeeding 

 generations, which, by the survival of the fittest, were 

 enabled not only to acquire the speech with the improve- 

 ments, but to make further improvements, all in like 

 manner to be transmitted to descendants of slightly 

 larger powers, the constant repetition of this process, 

 till speech as we know it was developed, furnishes us 

 with the means of learning by analogy the process by 

 which some of the more complex acquired traits in man 

 and lower animals have been developed. Like language, 

 these are individually acquired by each generation, and 

 like language have been developed and perfected during 

 many generations, and this especially when the acquired 

 trait is one which is only acquirable by the individual 

 slowly and with difficulty as speech is. 



The acquired mental traits of the lower animals are 



