126 BOOKS AND CURRENT LITERATURE 



Gager on the effects of radium, of Crocker and others on germination, 

 and of Richards, MacDougal, Osterhout, Newcombe, and Green. 

 One readily sees that other studies, which should rightly have found 

 a place in such a book, are missing, though inasmuch as it is intended 

 to comprehend methods rather than results, many of the most im- 

 portant works in the field of nutrition naturally would not be men- 

 tioned, since these frequently do not present new methods. We find 

 however that this expectation is wrong, and that, on. the contrary, 

 much space is devoted to the presentation of results, many of which 

 have been largely superseded by studies more recent' than those actu- 

 ally cited. It is therefore not captious perhaps to say that a wiser 

 selection of published results would have made the book more valu- 

 able. There are, moreover, indubitable indications that the author 

 has taken only minor note of American work. 



It would, however, be unjust to convey the impression that the 

 book is of secondary importance. It is distinctly valuable, for what- 

 ever the omissions may be, it contains a plentitude of material, and 

 it has the mission, conceived by the author, to bring the chemist and 

 the plant physiologist onto common ground. An additional value 

 of the book is found in a considerable number of useful tables in which 

 are brought together in condensed form a good many data, though, 

 as already indicated, some of these are superseded. Included among 

 them is, e.g., an extensive, table of color indicators, derived from Frie- 

 denthal, especially important for the more accurate study of sap 

 acidities. These valuable determinations, though well known to the 

 physical chemists, are not sufficiently appreciated by the botanists, 

 and it is in bringing many matters of similar value to their attention, 

 as well as in making an adequate summary for the biochemist of the 

 chemistry of nutrition from the physiologist's point of view that Grafe's 

 book will be especially appreciated. 



In conclusion it may be fairly stated that his work, which has called 

 for a very considerable and sustained effort on his part, contains a 

 large body of information of undoubted value. The chief criticism 

 is to be found in the very limited appreciation of the work of American 

 botanists, who, it is rightly believed, have made worthy achievements 

 in the field of plant nutrition. One gets the impression in running 

 through the book page by page in order to estimate the author's ac- 

 quaintance with the literature, that the citations of American studies 

 are more a matter of chance than systematic research. And there is 

 internal evidence that monographs which are known to have been 



