"Recapitulation. The growing frequency of surgically assisted births cannot be taken as evidence of a diminished birth capacity, but is closely connected with the growing number of doctors. Against the indications of a diminished birth capacity stand at the moment those which previously could be taken as pointing in the opposite direction. It would, therefore, appear that medical interference at birth has brought to the race advantages as to quantity and no drawbacks as to quality. But it is probable that the picture will change during the coming decades, because only then will the daughters of mothers who could not have brought forth living children without surgical assistance become themselves mothers. The renunciation of motherhood on the part of the women least suited for this function and the war against rickets might act as preventatives." The great anxiety about the elimination of the severest struggle for existence is based on the undoubtedly erroneous fundamental conception that the organism is a sorry product of necessity which can barely manage to maintain a laborious existence by the constant straining of all its faculties, and that it requires the continuous use of the whip of necessity to prevent an organism from giving way to its inherent tendency to degeneration. In fact, however, no organism is conceivable which has not the "Tendency" to maintain itself and to react accordingly. There are many facts which prove that a wealth of capacities and tendencies is dormant in organisms which for innumerable generations have not been active, or, perhaps, have, never functioned in every possible way, and that, therefore, if the occasion arises replacements or accommodations of an unprecedented character may occur. In an unprejudiced system of race-hygiene these facts must not be overlooked. The exhibition in this section gives two specially striking instances; the one from animal the other from plant life. [Sidenote: C 49] To begin with Figure C 49 gives a diagrammatic representation of the +development of the eye of a vertebrate+--after K. Kraepelin (taken from "Experimentelle Biologie II., T. v. Curt Thesing, Leipzig, Teubner, 1911")--which shows that the lens is formed out of an invagination of the cornea and the retina by an extension of the brain. In the lower part of the plate the various phases of the +reconstruction of the lens out of the iris+ are shown, after it had been removed by a cataract operation from the eye of a Triton larva. (This experiment was carried out by Gustav Wolff.)[A] Thus an organ which normally is not concerned with the formation of the lens takes charge of its regeneration. [Footnote A: Studies in the Physiology of Development II. Archiv. für Entwicklungs mechanic der Organismen, XII. Vol., 3 Part, 1901.]