Page:Popular Science Monthly Volume 25.djvu/397

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For, asserting the due claims of self is, by implication, drawing a limit beyond which the claims are undue; and is, by consequence, bringing into greater clearness the claims of others."

We have next to consider the duty of caring for others, as it presents itself in connection with the morality of happiness.—Knowledge.


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DISEASES OF PLANTS.

By D. P. PENHALLOW.

LECTURER IN BOTANY, MCGILL UNIVERSITY, MONTREAL.

STUDIES in vegetable pathology are by no means a recent development of science. So long ago as 1795, Schreger[1] issued a work treating of the various diseases then known, the work being in reality a compilation of the literature of the subject, which, up to that time, had been very much scattered. Then came a rather wide gap, until in 1833 linger issued his work entitled "Die Exantheme der Pflanzen und einige mit diesen verwandte Krankheiten der Gewächse." From that time until the present we find the well-known names of Meyen, De Bary, Sorauer, Hartig, Frank, and others linked with a tolerably copious literature on this subject. We find the Germans among the first, if not the very first, to recognize the desirability of pursuing questions of this kind from a scientific stand-point, though, aside from purely scientific considerations, these questions were forced upon the general attention of the country from an economical stand-point. It was recognized that the important interests involved in forest-growths were liable to be seriously impaired through the operation of disease, and that, even were this not the case, the interests involved could be most fully protected by the development of that knowledge which should secure the best oversight and care of forests in all respects. A wise policy, therefore, dictated the establishment of forestry stations, the duties of which included a study of the various diseases affecting trees.

In America hardly a serious thought has yet been given to such considerations, so far as they extend to the protection and preservation of our forests; but it seems probable that the movement to protect our forests from ruthless destruction at the hands of man, which is each year assuming more tangible shape, must ultimately embrace also an effort to have our trees studied according to strict scientific methods, for the purpose of determining their relation to disease and protecting them from injury. But, while we find the question unconsidered from the exact stand-point which first developed in Germany, we do find

  1. Erfahrungmässige Anweisung zur richtigen Kenntniss der Krankheiten der Wald und Gastenbäume, etc., Leipsic, 1795.