I. Haeckel and His Opponents

To what consequences the view of His leads may best be seen from his theory as to the orbital lobule, by which the so-called “rudimentary organs” of the organism were to be explained. These are parts which are present in the organism without possessing any sort of significance for its life. Thus man has a fold of skin at the inner corner of his eye which is without any purpose for the functions of the organ of sight. He possesses also muscles corresponding to those by which certain animals can move their ears at will. Yet most people cannot move their ears. Some animals possess eyes which are covered over with a skin and thus cannot serve for seeing. His explains these organs as being such, to which “up to the present it has not been possible to assign any physiological role, analogous to the snippets, which, in cutting out a dress, cannot be avoided even with the most economical use of the stuff.” The evolution theory gives the only possible explanation of them. They are inherited from remote ancestors, in whom they subserved a useful purpose. Animals which to-day live underground and have no seeing eyes, descend from such ancestors as once lived in the light and needed eyes. In the course of many generations the conditions of life of such an organic stock have changed. The organisms have adapted themselves to the new conditions in which they can dispense with organs of sight. But these organs remain as heirlooms from an earlier stage of evolution; only in the course of time they have become atrophied, because they have not been used. These rudimentary organs[^9] form one of the strongest means of proof for the natural theory of evolution. If any deliberate intentions whatever had ruled in the building up of an organic form, whence came these purposeless parts? There is no other possible explanation of them, except that in the course of many generations they have gradually fallen into disuse.