abnormal sexual life and then to discourage the popular circulation of the extensive works which only certain physicians and social reformers need. I know that there is some difference of opinion as to the effect of such literature. I know many prominent educators and physicians who would keep the extensive works on the psychopathology of sex out of the hands of all general readers; but I also know a few who see no possibility of danger in widespread circulation of such books. [Sidenote: Limited knowledge of the abnormal.] Looking at all sides of the present situation, it is my personal conclusion that every one should learn first the scientific facts regarding normal processes connected with the sexual system; and then for the general reader there should be only a limited amount of warning knowledge regarding the dangers of sexual abnormalities. VI SEX-INSTRUCTION FOR PRE-ADOLESCENT YEARS [Sidenote: Periods of early life.] In Sec. 8 of the Report of the Committee of Three of the American Federation for Sex-hygiene, by Morrow and others, the life of the child was divided into four periods, namely,--under six years, from six to twelve, twelve to sixteen, sixteen to maturity. This division now seems to me to be too arbitrary, and I have come to believe that it is more helpful to consider sex-instruction for three periods as follows: pre-adolescence (ending at eleven to fourteen years); early adolescence (twelve to sixteen years for girls, thirteen to seventeen for boys); later adolescence (sixteen to twenty-one for girls, eighteen to twenty-five for boys). Sec. 25. _Elementary Instruction and Influence_ [Sidenote: Nature-study.] The life-histories of plants and animals as taught in the best nature-study[13] are important in forming attitude towards reproduction and giving a basis for simple and truthful answers to the child's questions as to the origin of the individual human life. The publications listed in the last section of this book under the headings "For Girls" and "For Boys" will help parents and teachers. There is need of little private hygienic instruction, but of much guidance away from harmful habits. This will be indicated in the next section which considers masturbation as it concerns children of both sexes and all ages. [Sidenote: Protection.] The protection of children from corrupting influences is an important work of sex-education in pre-adolescent years. Probably the greatest safety lies in parents giving simple facts regarding reproduction and in cultivating confidence so that any accidental contact of their children with vulgarity will be counteracted in advance. Many parents, especially mothers, have found this possible. [Sidenote: Girls' preparation for puberty.]