The digestive apparatus, then, affords abundant proof of the imperfection and disharmony of our nature. Moreover, there are many other proofs, as I shall show in the chapters to follow. CHAPTER V DISHARMONIES IN THE ORGANISATION AND ACTIVITIES OF THE REPRODUCTIVE APPARATUS. DISHARMONIES IN THE FAMILY AND SOCIAL INSTINCTS I _Remarks on the disharmonies in the human organs of sense and perception.—Rudimentary parts of the reproductive apparatus.—Origin and function of the hymen_ The digestive organs are not alone amongst the parts of the human body in exhibiting a greater or lesser disharmony. More than fifty years ago, a great German physiologist, Johannes Müller, showed that although the human eye was regarded as a very perfect organ, its power of correction for aberration of light was poor. Helmholz, another famous German man of science, stated that the optical study of the eye brought complete disillusion. “Nature,” he said, “seems to have packed this organ with mistakes, as if with the avowed purpose of destroying any possible foundation for the theory that organs are adapted to their environment.” Not only the eye, but the other organs by means of which we are conscious of the outside world, present natural disharmony. Therein lies the cause of our want of certainty about the sources of our perceptions. Memory, the faculty that registers our mental processes, becomes active much later than other faculties lodged in the brain. If the new-born human child were relatively as well developed as the young guinea-pig, it is probable that we should know far more as to the history of our consciousness of the external world. But without lingering over the disharmonies in our senses and faculties, I shall pass at once to a consideration of the apparatus for maintaining the species. I have shown that the alimentary tract, the chief organ involved in the maintenance of the individual life, affords no proof of the theory that human nature is perfect. Is it the case that the organs of reproduction give a better result? When I wished to describe the most perfect examples of harmony to be found amongst plants, I chose the mechanism by which fertilisation is accomplished in flowers. The persistence of the species is secured, in the case of flowers, by a marvellous series of structures and functions.