CHAPTER XI

INTRODUCTION TO THE SCIENTIFIC STUDY OF DEATH 262

Theory of the immortality of lower organisms—Immortality of the sexual cells in higher organisms—Immortality of the cellular soul—Occurrence of natural death in the case of certain animals—Natural death in the Ephemeridæ—Loss of the instinct of preservation in adult Ephemerids—Instinct of life in the aged—Instinct of natural death in man—Death of old men in biblical times—Changes in the instincts of man and lower animals