Page:Popular Science Monthly Volume 83.djvu/153

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S a principle of evolutionary theory, it may be stated that the environment stands to the organisms within it in one group of relations during the long evolution of races and species. The part played by the environment in the development of an individual is equally important, but so unlike in character that it must be treated independently. Phylogeny and ontogeny are governed by their own laws; yet they are elements in one harmonious whole. If carefully studied, either will show the part objective conditions play in progress. I have already touched upon phylogenetic problems in earlier articles, where I tried to show that while the inheritance of characters follows biologic laws, the release of characters takes place under the stimulus of environing conditions. The external environment is not active at conception or when characters are formed before birth. Each individual must be brought into contact with external conditions through his own experience to evoke the characters heredity has given him. He recapitulates the history of his ancestors with regularity; yet the biologic effects of this race experience may lie dormant within him, if external stimuli do not evoke them at the proper time. The individual in whom they are undeveloped is retarded, and shows in his conduct defects which in the contest of life put him behind other persons of like heredity but with a more stimulating environment.

The principles of ontogeny can not, however, be elucidated in this way. They are to be traced in the epochs of child development rather than in those of race evolution. If the environment has no influence, such studies are a waste of time; but if environing conditions have influence their power over the successive stages of child growth may be detected. The early stages will be less under environment control. But each later state would be more subject to the retardations and accelerations imposed by objective conditions. Each environmental shortcoming would be reflected in some personal defect; and every acceleration due to favorable conditions should be measurable in increased vigor. Men reflect their defects in appearance, their perfections are revealed in their activity not in their bodily structure.

In attempting to show the relation of environmental control to the various stages of child development I shall rely upon this principle. Biologic characters are positive and show themselves in normal persons. Defects, being negative, indicate the absence of characters or an