ARTICLE IV
SPECIES AS TO VARIATION, GEOGRAPHICAL DISTRIBUTION, AND SUCCESSION
Alphonse De Candolle's Study of the Oak Genus.—Variability of the Species.—Antiquity.—A Common Origin probable.—Dr. Falconer on the Common Origin of Elephants—Variation and Natural Selection distinguished.—Saporta on the Gradation between the Vegetable Forms of the Cretaceous and the Tertiary.—Hypothesis of Derivation more likely to be favored by Botanists than by Zoologists.—Views of Agassiz respecting the Origin, Dispersion, Variation, Characteristics, and Successive Creation of Species contrasted with those of De Candolle and others—Definition of Species—Whether its Essence is in the Likeness or in the Genealogical Connection of the Individuals composing a Species