WINFIELD S. HALL, December, 1906. Chicago. CONTENTS. Chapter I. REPRODUCTION FROM THE STANDPOINT OF BIOLOGY. 1. General Activities of Living Organisms 11 A. The Egoistic Activities 12 B. The Phyletic Activities 13 a. Reproduction 13 b. Support and Protection of Offspring 13 c. Support and Protection of Weaker Members of Society 15 2. Some General Principles of Biology 15 A. Sacrifice and Compensation in Egoistic Activities 15 B. Sacrifice and Compensation in the Phyletic Activities 16 a. Lower Organisms 16 b. Higher Organisms 19 C. Summary of Principles 24 a. The propagation of offspring and the protection and support of the young and defenseless, always involve sacrifice on the part of the parents and the stronger members of the race 24 b. Sacrifice made consciously for the race is, in the natural order of things, compensated 24 Chapter II. ADOLESCENCE IN THE MALE. 1. Physical Changes 28 A. General Changes in the Body 28 a. Pilosity 28 b. The Voice 29 c. Bone, Muscle and Gland 30 B. The Genital System 32 a. Structural Changes 32 b. Functional Changes 32 2. Psychical Changes 33 A. Play and Work 33 a. Sports 33 b. Productive Employment 34 B. Society 35 C. Religion 36 Chapter III. ANATOMY AND PHYSIOLOGY OF THE MALE GENITAL ORGANS.