=Relative Power of Fungicides.=--Mr. F. L. Stevens has published, in the Botanical Gazette, an account of experiments made for the purpose of establishing with some degree of accuracy the strengths of various solutions which are necessary to prevent the growth of fungous spores. The bearing of this question upon the relation of a fungicide to its efficiency is apparent. As among the general results the author finds that mercuric chloride is the strongest chemical used in its toxic effect upon the fungi, while potassium cyanide is remarkably weak considering its great toxic action on animals. Alcohol and sodium chloride have a stimulating effect. Various fungi offer different resistance to poisons, and the limits of resistance will vary in the same species. The spores of fungi are less susceptible than the roots of seedlings. A chemical may be twice as powerful as another against one fungus, while in acting upon another fungus an entirely different ratio may be sustained. An occasional spore may germinate and grow quite normally in a solution that prevents hundreds of normal spores around it from germinating. Penicillium as a nutrient medium offered greater resistance to poisons than did any of the other fungi worked upon. Uromyces did not diminish in vigor of growth with the increased strength of the poison, but the percentage of spores that germinated was diminished. In general, the results of the action of the chemicals were in accord with the theory of hydrolytic association. Incidentally new evidence bearing upon the theory of the hydrolytic dissociation of the molecule was adduced, together with facts that may throw some light upon the structure of the cell wall.