Many parents who believe in sex-education for their children hold that the mothers should give all necessary hygienic guidance and teach the elementary facts of life to the children of both sexes in the pre-adolescent years, but that with the dawn of adolescence the girls should continue to be instructed by their mothers, while the boys should be guided by their fathers. So far as girls are concerned, this seems to be a fairly good plan; but nine times out of ten it is not best for the boys for several reasons: First, the sudden change of attitude on the part of the mother will surely impress upon the boy that there is something about sex in boys that even his mother dares not talk over with him. At about this same time when the mother begins to avoid the sex question with her boy, he will surely begin to get vulgar information and impressions from his boy companions. He will in all probability begin to hear the impure and obscene stories and vulgar language that are so common among many men and boys, and he will be sure to learn that the vulgarity which he hears must not be repeated in the presence of his mother and sisters. It is a most critical time in the mental attitude of the boy. His mother has so far been directing him towards purity and then suddenly sets him adrift. If there is ever a time in a boy's life when he needs intimacy with his mother, it is in the early adolescent years of twelve to fourteen. A strong mother's heart to heart guidance at that time will influence the boy more than all the sex-education which the schools and colleges combined can ever hope to offer. Such is the problem of home teaching for adolescent boys. I emphatically protest against the foolish and even dangerous idea that because a boy is beginning to metamorphose into a man his mother should cease to help him with the problems of sex. Lucky is that adolescent boy whose mother realizes her duty and her opportunity and holds him as intimately as if he were a girl of corresponding age. Sec. 20. _Selecting Teachers for Class Instruction_ The references to "the teacher" in the following are primarily applicable to those who may be called upon to give sex-instruction as class work in schools, colleges, churches, the Y.M.C.A., the Y.W.C.A., and other educational organizations. The chief question for discussion in this lecture is that of selecting the teacher of those phases of sex-instruction that are directly related to human life, that is, personal sex-hygiene and sex-ethics. So far as biological facts of sex are concerned, there are no special problems such as may not be handled by teachers of biology in general according to the accepted methods (see Lloyd and Bigelow, "Teaching of Biology in the Secondary School" and Bigelow, "Teacher's Manual of Biology"). [Sidenote: Regular teachers if possible.]