To sum up, then, biological investigation in the first place shows us how certain abnormalities of sexual psychology may be more easily interpreted as caused by comparatively simple physical abnormalities than by the more complex distortions of psychological origin dealt with by psycho-analysis. In the second place, by giving us a broader _aperçu_ than can otherwise be gained over the evolution of sex and the direction visible in biological history, it clears up to a certain extent some of the difficulties which the discoveries of the psycho-analytic school have rendered acute. If the changes in the relation of the sex instinct to the rest of the mind, which I have spoken of above as being in operation at present, should one day progress so far as to be more or less carried through in a majority, or in a dominant section of the population, the whole outlook of society towards the sex problem would be changed, and the laws and institutions and customs connected with it completely remodelled. The most pressing task of those who are thinking over the problem of sex in human life will often be the relief of suffering and the removal of abuses: but the broader view should never be forgotten, and every attempt should be made to think constructively with a view to realizing the enormous possibilities that such a change would bring about. BIBLIOGRAPHY Blair Bell, ’16. “The Sex Complex.” London, 1916. Carr-Saunders, ’22. “The Population Problem.” Oxford, 1922. Crew, ’23. Proc. Roy. Soc. (B.). London, 1923. Cunningham, J. T., ’00. “Sexual Dimorphism in the Animal Kingdom.” London, 1900. Doncaster, L., ’14. “The Determination of Sex.” Cambridge, 1914. East and Jones, ’19. “Inbreeding and Outbreeding.” Philadelphia, 1919. Ellis, Havelock, ’10. “Studies in the Psychology of Sex.” Philadelphia, 1910. Freud. “The Psychology of the Unconscious.” Goldschmidt, R., ’23. “The Mechanism and Physiology of Sex-Determination.” London, 1923. Harrow, B., ’23. “Glands in Health and Disease.” London, 1923. Howard, E., ’20. “Territory in Bird Life.” London, 1920. Huxley, ’14. (Reversed Pairing, Grebe) Proc. Zool. Soc. London, 1914. Huxley, ’23. (Courtship and Display) Proc. Linnean Soc. London, 1923. Jung, ’20. “Analytical Psychology.” London, 1920. Lipschütz, ’19. “Die Pubertätsdrüse.” Bern, 1919. Marshall, ’23. “The Physiology of Reproduction.” (2nd Ed.). Cambridge, 1923. Meisenheimer, J., ’21. “Geschlecht und Geschlechter.” Jena, 1921. Morgan, ’19. “The Physical Basis of Heredity.” Philadelphia, 1919. Rivers, ’20. “Instinct and the Unconscious.” Cambridge, 1920. Selous, E., ’20. (Moorhen) _Zoologist_ [4] 6. London, 1902. Steinach J., ’20. Verjüngung, Leipzig, 1920. Stopes, Marie. “Married Love.” Tansley, ’20. “The New Psychology.” London, 1920.