Note 91 — Chapter XII · HOW THE RACES WERE PHYSIOLOGICALLY SEPARATED, AND THE DIFFERENT VARIETIES FORMED BY THEIR INTER-MIXTURE. THEY ARE UNEQUAL IN STRENGTH AND BEAUTY

Alexander von Humboldt does not think that this hypothesis can apply to the migration of plants. “What we know,” he says, “of the deleterious action exerted by sea-water, during a voyage of 500 or 600 leagues, over the reproductive power of most grains, does not favour the theory of the migration of vegetables by means of ocean currents. Such a theory is too general and comprehensive” (Examen critique de l’histoire de la géographie du nouveau continent, vol. ii, p. 78).