Now, can we conceive of the origin of bow and arrow in an analogous way? Surely this weapon also was not devised in all its parts at a single time. The man of nature, pressing his way through the dense underbrush of the forest and experiencing in person the hard blows of branches that he has bent back, gains a lively impression of the elastic power of bent wood. How easily the attention is forced to the observation that this effect increases when the wood is bent out of its natural shape, appears strikingly in the case of a kind of bow found in Asia and the Asiatic islands. The bow is here constructed out of a piece of wood bent by nature, not in such a way, however, that the natural curve of the wood forms the curve of the bow, but contrariwise. Thus arises a _reflexive_ bow, whose elastic power is, of course, considerably increased. In order that such a bow may be bent back more easily, some people of a more advanced culture construct it out of several layers of wood, horn, sinew, or the like. Having first observed the powerful impulsive force which a rod gains through being bent, it was a simple matter to render this force permanently available by bending the rod back and binding its ends together with a cord of bast, or, if bamboo was used, with strips torn from the bamboo itself. Thus originated the common form of the bow. Next, it was, of course, easy to observe that the bowstring thus contrived would communicate a powerful impetus to a lighter piece of wood placed against it. In addition to the bow, we then have the arrow, which is hurled into the distance by the combined propelling power of the bow and its string. But at this point a new factor appeared, clearly indicating that several motives generally co-operated in the case of such so-called primitive inventions. In these inventions nature itself played no less a part than did the inventive genius of the individual. The arrow but rarely consists merely of a piece of wood one of whose ends is somehow pointed or provided with a stone head, or, at a later period, with an iron head. As is well known, the other end is feathered, either with genuine bird feathers or, as in the case of the pygmies of Central Africa, with an imitation of bird feathers made of palm-leaves. The feathers are usually supposed to have been added to insure the accurate flight of the arrow. And this accuracy is, indeed, the resultant effect. As in the case of the boomerang, however, we must again raise the question: How did man come to foresee this effect, of whose mechanical conditions he had, of course, not the slightest knowledge? The solution of this problem probably lies in the fact of an association of the discharged arrow with a flying bird that pierces the air by the movement of its feathers. Thus, in the arrow, man copied the mode of movement of the bird. He certainly did not copy it, however, with the thought that he was causing movement in a mechanical way. We