Notes and Comment. 51 



are no doubt in part the result of several fortunately chosen 

 principles which have served to guide the working out of new 

 ideas and methods; but particularly is this progress to be attrib- 

 uted to the growing tendency to replace the qualitative method 

 of investigation by the quantitative. A recent book by Philip * 

 is designed as a "sketch of the physico-chemical basis for this 

 modem treatment of biological and physiological problems," 

 and is indeed but an introduction to some of the most important 

 subjects of physical chemistry. Most fully treated are: the 

 gas laws, osmotic pressure, electrolytic dissociation, the theory 

 of solution and colloidal solutions. The total avoidance of 

 mathematics necessitates rather lengthy expositions which, 

 however, are written in a very readable style. Each phvsical 

 chemical principle is illustrated with several most fortunately 

 chosen applications from the biological sciences. The incom- 

 pleteness of the work, even as an elementary treatment, is strik- 

 ing, as illustrated by the absence of a discussion of chemical 

 equilibrium in a heterogeneous system, hydrolysis and of Fara- 

 day's laws, although all of these principles are employed in the 

 exposition of other subjects. — Herman A. Spoehr. 



NOTES AND COMMENT. 

 The arrangement by which Professor R. A. Harper goes to 

 the University of California for the second semester of the pres- 

 ent year and Professor G. J. Peirce, of Stanford, takes his place 

 in Wisconsin is one that is to be highly commended, and it is to 

 be hoped and expected that the advantages of such an exchange 

 between botanical departments of American universities will be 

 so manifest as to lead to more frequent arrangements of this kind. 



The symposium on plant pathology held at the recent an- 

 nual meeting of the Botanical Society of America affords some 

 indication of the progress that has been made in this department 

 of investigation within a decade. Time was, not so many years 

 ago, when a student of plant diseases devoted his attention 

 wholly, or almost wholly, to parasitic fungi. Later the study of 

 plant pathology, as indicated by what was undertaken by its 

 most advanced representatives, seemed, in great measure, a 



♦Philip, James C. — Physical Chemistry. Its Bearing on Biology and Medecine. London 

 Edwin Arnold, 1910. 



