SEX AND HEREDITY 1277 The Origin of Sex 1279 A Rational View of Sexual Health 1285 Embryological Growth--Prenatal Culture 1289 Heredity 1293 What Heredity Is 1295 Summary of Facts regarding Sex and Heredity 1297 _Lesson XXI_ REST AND SLEEP 1299 Rest 1301 The Old Physiology 1305 Rest and Re-creation 1306 Sleep 1308 Some Reasons 1310 Oxidation and Air 1312 _Lesson XXII_ A LESSON FOR BUSINESS MEN 1315 A Good Business Man 1320 The Routine Life of the Average Business Man 1322 Some Suggestions for a Good Business Man 1324 _Lesson XXIII_ EXERCISE AND RE-CREATION 1327 Exercise 1329 Constructive Exercises 1330 Exercise for Repair 1331 Physiology of Exercise 1333 Systems of Physical Culture 1338 Program for Daily Exercise 1343 Re-creation 1346 _A chest of miracles, Close-packed and all secure, the unstable mass Supported from a ruinous collapse Or helpless flexion, by a spinous pile Rigid as oak, yet flexile as the stem of the nodding flower. Within, a nest of wonders, separate tasks Each organ faithfully performing, still From day to day harmoniously smooth And uncomplaining, but for hindrances Or ruinous urgence. Thou hast wisely said, Melodious singer of old Israel, "I am fearfully and wonderfully made."_ E. C. LESSON I THE INTERRELATION OF FOOD CHEMISTRY AND PHYSIOLOGICAL CHEMISTRY FOOD CHEMISTRY AND PHYSIOLOGICAL CHEMISTRY UNITED The human body is composed of fifteen well-defined chemical elements. A normal body weighing 150 pounds contains these elements in about the following proportions: POUNDS OUNCES GRAINS