by the lapsing of ancestral inborn variations, and man would degenerate 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 improvements occupying long ages, during which also occurred a corresponding and contemporaneous evolution of the structures which subserve speech and thought. If, then, the knowledge 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 perfection, Avould 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, during innumerable generations, the one generation transmitting 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 improvements, but to make further improvements, all in like manner to be transmitted to descendants of slightly larger jewel's, 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
