PART I.—Do Varieties in Plants wear out, or tend to wear out?—The Question considered in the Light of Facts, and in that of the Darwinian Theory.—Conclusion that Races sexually propagated need not die of Old Age.—This Conclusion inferred from the Provisions and Arrangements in Nature to secure Cross-Fertilization of Individuals.— Reference to Mr. Darwin's Development of this View
PART II.—Do Species wear out, and, if not, why not?—Implication of the Darwinian Theory that Species are unlimited in Existence.—Examination of an Opposite Doctrine maintained by Naudin.—Evidence that Species may die out from Inherent Causes only indirect and inferential from Arrangements to secure Wide Breeding—Physiological Import of Sexes—Doubtful whether Sexual Reproduction with Wide Breeding is a Preventive or only a Palliative of Decrepitude in Species.— Darwinian Hypothesis must suppose the Former