CHIEFLY rilYSIOLOGICAL.
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every seven years, science has long since exploded. “The matter,” said Mi. John Goodsir, “ of the organized frame to its minutest parts is in a continual flux.” Our bodies are never the same for any two successive days. The feet that Mary shall dance with next Christmas Eve will not be the same feet that bore her triumphantly through the previous Christmas holidays. The brain that she learns German with today does not contain a cell in its convolutions that was spent in studying French one year ago. Whether her present feet can dance better or worse than those of a year ago, and whether her present brain can do more or less German and French than the one of the year before, depends upon how she has used her feet and brain during the intervening time, that is, upon the metamorphosis of her tissue.
From birth to adult age, the cells of muscle, organ, and brain that are spent in the activities of life, such as digesting, growing, studying, playing, working, and the like, are