. Botany; principles and problems. Botany. 236 BOTANY: PRINCIPLES AND PROBLEMS was the chief factor in convincing scientific men of the truth of the evokitionary theory in general; and whatever we may think today of the merits of some of Darwin's hypotheses, we recognize that the thoroughness of his scientific work and its revolutionary effect on all lines of biological thought entitle him to rank as the first great evolutionist. Darwin based the theory of Natural Selection upon three main facts: Variations and their inheritance; over-production of ofT-. FiG. 134.—Charles Darwin, 1809-1882. sp
. Botany; principles and problems. Botany. 236 BOTANY: PRINCIPLES AND PROBLEMS was the chief factor in convincing scientific men of the truth of the evokitionary theory in general; and whatever we may think today of the merits of some of Darwin's hypotheses, we recognize that the thoroughness of his scientific work and its revolutionary effect on all lines of biological thought entitle him to rank as the first great evolutionist. Darwin based the theory of Natural Selection upon three main facts: Variations and their inheritance; over-production of ofT-. FiG. 134.—Charles Darwin, 1809-1882. spring with the consequent "struggle for existence"; and the "survival of the ; He was vividly impressed by the occurrence of variations in all animals and plants and studied them carefully, endeavoring to discover their causes. Like other scientific men of his day, Darwin did not clearly understand the mechanism and laws of inheritance. He believed, at least in his earlier work, that "acquired" characters may be transmitted to'offspring, but this belief did not form the essential basis for his theory, as it did for that of Lamarck. The main fact which he emphasized was that variations in all directions are exceedingly abundant and that in many cases they are certainly transmitted by inheritance to the offspring. The overproduction of progeny in plants and animals forms the next step in the theory. If all seeds which are produced were to. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Sinnott, Edmund Ware, 1888-. New York, McGraw-Hill
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