Rhizoctonia

ganic salt relations of plants, and relation of plants to climatic conditions. A quotation from the book expresses the point of view under which the work of the laboratory is being conducted. To summarize the last few paragraphs, our operations have been and are directed toward a dynamic analysis of plant activity. The point of view here employed may perhaps be envisaged if the reader will regard the living plant in somewhat the same general way as he might any complex machine, such as a gasoline motor, for example. To understand its working, one must understand how and how much various conditions may effect a machine; in short, he must become an engineer with respect to that particular mechanism. Dynamic plant physiology may be said, then, to be engineering science as applied to the living plant. It can progress, then, only through quantitative studies, through the comparison of efficiency graphs and curvetracings made by recording instruments, through the mathematical interpretation of relations between conditions and process rates, etc., and it is with just this sort of studies that our investigations have to do.