X CONTENTS 



CHAPTER. PAGE 



XXVII. The Blood and Circulation 259 



XXVIII. Respiration 269 



XXIX. Excretion . 277 



XXX. Internal Secretions and the Ductless Glands 280 



XXXI. The Skin ' 283 



XXXII. The Skeleton and the Muscles 287 



XXXIII. The Nervous System 294 



XXXIV. The Organs of Sense 304 



XXXV. Alcohol and Tobacco 311 



XXXVI. Bacteria and Disease 317 



PART III. GENERAL FEATURES AND ADAPTATIONS. 



XXXVII. The Perpetuation of Life 331 



XXXVIII. The Evolution of Life 341 



XXXIX. Divergence and Adaptation 362 



XL. Heredity and Human Improvement 370 



