BOOKS AND CURRENT LITERATURE 159 



growth than the last week at Easton. The maxima of temperature 

 and growth occurred about a month earher at Oakland than at Easton 

 These are both facts of great importance in the application of pheno- 

 logical data to agricultural problems. 



The evidence for soy-bean showed the growth of the first fortnight 

 to be controlled by temperature and that of the second fortnight by the 

 rainfall-evaporation ratio. The securing of facts of this character will 

 make invaluable additions to our meagre knowledge of what* may be 

 designated as the physiological life histories of plants. McLean's 

 work emphasises the fact that we must reckon not only with the com- 

 plexities of the en\dronmental conditions but also with the changes in 

 the requirements of the plant itself from germination to maturity. 

 The publication of liis results mth Windsor bean, corn, and wheat 

 will be awaited with interest, for in them we mil doubtless have to 

 face a third set of complexities^those by which various species of 

 plants differ in their environmental requirements and in their onto- 

 genetic changes of requirement. — Forrest Shreve. 



Laboratory Manual of Soil Biology. — The last five or six years 

 have witnessed the appearance in this country of many laboratory 

 manuals or guides for the student of soil microbiology. Prior to the 

 pubhcation of the Soil Bacteriology Laboratory Guide by Lipman 

 and Brown in 1911, there were no publications of the sort in English. 

 Since then, however, there have appeared in quick succession the 

 number above given. Some of these manuals, to be sure, comprised 

 exercises in several branches of agricultural bacteriology, including 

 soil bacteriology, but at least three have been devoted solely to the 

 last named subdivision of bacteriologJ^ 



The subject of the present re\dew is the most recent addition to 

 the group of little volumes referred to.^ It consists primarily of the 

 usual exercises given to the advanced student of soils in our labora- 

 tories on ammonification, nitrite formation, nitrate formation, deni- 

 trifieation, symbiotic and non-symbiotic nitrogen fixation, cellulose 

 decomposition, sulfofication, desulfofication, iron oxidation, and car- 

 bon dioxide production. Added to these as new features, are exercises, 

 on the study of soil protozoa, soil fungi, enzyme activity of soil mi- 

 croorganisms and more elaborate directions for chemical and bacterio- 

 logical methods, and for the preparation of media, than are given in 



1 Whiting, A. L., Laboratory Manual of Soil Biology. Pp. ix + 143. John 

 Wiley and Sons, New York and London, 1917 ($1.25). 



