DISEASES OF PLANTS. 385 



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 pre- 

 sents itself in connection with the morality of happiness. — Knowledge, 



DISEASES OF PLANTS. 



By D. p. PENH allow, 



LZOTUfiEB nr BOTANY, MO GILL UNIVEBSITY, MONTEEAL. 



STUDIES in vegetable pathology are by no means a recent devel- 

 opment of science. So long ago as 1795, Schreger * 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 Gewachse." 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 



* Erfahrungmassige Anweisung zur richtigen Kenntniss der Krankheiten der Wald- 

 und Gastenbaume, etc., Leipsic, 1795. 

 VOL. xxv. — 25 



