Page:Popular Science Monthly Volume 7.djvu/682

662 with lines so deep as to determine the direction of conduct with the greatest certainty. Then habit becomes instinct. The individual no longer forms the structure, but inherits it ready formed. The actions are no longer learned by practice, they are already predetermined by the inherited structure.

We see illustrations of this process in the artificial formation—the deliberate manufacture—of instincts in domestic animals by human training and human selection. We know that the instincts of the pointer and the shepherd's dog have been formed in this way. The great ancestor of all the pointers, before he was a pointer, was trained with much coaxing and many beatings to do certain things. The result was doubtless any thing but satisfactory. Still a habit was formed, and, as we must believe, a corresponding brain-structure. The pups of this dog were again trained, still with difficulty, but with less difficulty than before, because the habit-structure was partially inherited. The best-trained of this generation are selected, and their pups again trained. The process is still easier, because the habit-structure is more completely inherited, and the result is more satisfactory, because the structure is more decided. Thus the improvement goes on from generation to generation, until finally, in the purest bloods, i. e., those having the longest line of well-trained ancestry, without mixture with effacing bloods, little or no training at all is required; the habit-structure is almost perfectly transmitted. Perhaps in this case transmitted habit never becomes perfect instinct; probably the best-blooded pups still require training. But this is because the process has not been continued long enough, the breeding has not been true enough, and the selection careful enough.

Now, if pointers or shepherds' dogs should become wild, their instincts would quickly be destroyed by natural selection, because they are not useful, but, on the contrary, hurtful, in the wild state. But, suppose they were useful in the struggle for life, then the habit thus acquired would be transmitted, and become strengthened with every generation, until it would become as perfectly fixed and invariable as any, even the most perfect instinct.

Now, it is precisely in this way that the wonderful instincts of bees and ants and the wonderful instinctive coördination of muscles in ruminants and gallinaceous birds have been formed, except that in these cases natural training and natural selection have operated instead or human training and human selection. The great ancestor of all the bees, before the distinctive characters of the bee yet existed, was doubtless destitute of the wonderful instincts which we now find. These have been gradually formed and improved from generation to generation through many hundred thousands of years.

It is difficult to imagine, much more to express, all the steps of this process. I will, therefore, illustrate it in the following manner: We have seen that wise conduct is a product of intelligence and