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been done before. If the preceding argument is admissible, new light will be thrown 
not only on the cases of parasitism referred to, but also on the behavior of the host 
in its struggle for existence with the factors of the inorganic environment, generally. 
Finally, the bearing of the discussion on other parasitic diseases is 
considered, and short but very suggestive paragraphs are given to a 
number of fungi causing diseases; among them Phytophthora infestans , 
Nectrias and wood destroying Hymenomycetes, the Ustilaginese and 
Uredinese. Copious footnotes add to the value of the paper, which 
should be in the hands of every student of plant diseases.—W. T. 
Swingle. 
