Only recently has it been pointed out that one's attitude towards sex may be profoundly influenced by reading certain general literature that holds up high ideals of love and sex and life. It will be most convenient to consider the influence of literature on sex-instruction in another lecture (Sec. 23). [Sidenote: Teaching personal sex-hygiene.] Now let us consider the general bearings of the personal sex-hygiene demanded by the second aim. For children under ten and twelve the necessary hygiene should be presented personally (see Sec. 25). For young people of adolescent years there are four possible ways of instruction in personal sex-hygiene: (1) It may be added naturally to a course or series of lessons in general hygiene including the problems of health for all systems of organs. (2) It may be included in a study of vertebrate and human reproduction in a course of biology or zoology. (3) It may be presented by a special lecture that is independent of all regular courses of study. (4) Special booklets may be put into the hands of young people. Let us now examine each of these ways: [Sidenote: Sex-hygiene in general hygiene.] (1) Sex-hygiene as a natural part of a series of lessons in general hygiene is most satisfactory when preceded by biological nature-study or high-school biology in which life-histories of organisms have been studied for the sake of attitude. At present we lack satisfactory textbooks for this kind of correlation. There is a strong reaction against independent courses of hygiene in high schools, and the next plan is becoming more common. [Sidenote: Hygiene in biology.] (2) The inclusion of the necessary hygiene of all organs in courses of biology or zoology that have emphasized physiology and its bearings on health is the best arrangement so far proposed and tested in practice. It has been tried with success by Dr. W.H. Eddy in the High School of Commerce, New York City, and by other high-school teachers working along the same lines. The arguments for teaching general hygiene on a biological basis have been presented in the last chapter of "The Teaching of Biology in Secondary Schools" by Lloyd and Bigelow, and put in textbook form in the "Applied Biology" and "Introduction to Biology" by M.A. and Anna N. Bigelow. However, personal sex-hygiene is not included in these textbooks, because educational and public opinion do not yet stand for such radical lessons in books for schools. [Sidenote: Special lectures on hygiene.]