Page:Popular Science Monthly Volume 43.djvu/174

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162
THE POPULAR SCIENCE MONTHLY.

gation in these all-important years of the beginnings of new commonwealths based upon new industries? Millions of acres of land are forever worthless without water. Who shall own the streams and reservoirs — a few far-sighted men, or the people themselves? Irrigation journals and conventions of irrigators discuss the matter from the standpoint of the present, and endeavor to shape legislation to profitable ends. The slow, dumb masses have not yet recognized the magnitude of the problems involved. An effort is being made to have the United States give all the arid lands to the several States and Territories in which they lie, but the plan is dangerous. Only the Federal Government can protect the sources of water supply; utilize, reservoir, and distribute that supply, and unite water and land in an indissoluble marriage bond.


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THE INADEQUACY OF "NATURAL SELECTION."

By HERBERT SPENCER.

[Concluded.]

THIS very pronounced opinion will be met on the part of some by a no less pronounced demurrer, which involves a denial of possibility. It has been of late asserted, and by many believed, that inheritance of acquired characters can not occur. Weismann, they say, has shown that there is early established in the evolution of each organism, such a distinctness between those component units which carry on the individual life and those which are devoted to maintenance of the species, that changes in the one can not affect the other. We will look closely into his doctrine.

Basing his argument on the principle of the physiological division of labor, and assuming that the primary division of labor is that between such part of an organism as carries on individual life and such part as is reserved for the production of other lives, Weismann, starting with "the first multicellular organism," says that — "Hence the single group would come to be divided into two groups of cells, which may be called somatic and reproductive — the cells of the body as opposed to those which are concerned with reproduction" (Essays upon Heredity, p. 27).

Though he admits that this differentiation "was not at first absolute, and indeed is not always so to-day," yet he holds that the differentiation eventually becomes absolute in the sense that the somatic cells, or those which compose the body at large, come to have only a limited power of cell-division, instead of an unlimited power which the reproductive cells have; and also in the