Chapter III: 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