244 ' BOOKS AND CURRENT LITERATURE 



sophical interpretation of data. . For this reason, as well as because 

 of its intrinsic worth, Dr. Raymond Pearl's Modes of Research in 

 Genetics is especially interesting and valuable. ^ Although problems 

 in heredity have been for ages attractive fields for speculation, the 

 scientific attack upon the general subject of genetics, in a systematic 

 way and from all sides, has just begun. It is particularly fortunate 

 for. the science to have near its beginning, a summarization of the 

 modes of research and an estimation of the validity of the deductions, 

 for it will help to curb the careless tendency toward over valuation of 

 certain methods of work and will call attention to the need of careful, 

 logical thought. Such a book as this in almost any other branch of 

 scientific work might have prevented some of the numerous ill advised 

 articles which have so disfigured the history of science and which 

 have precipitated imdignified discussions. The fundamental value of 

 this book is very little lessened if one does not agree with the conclusions 

 set forth because it will have stimulated thoughtful consideration of 

 the problems involved. As is natiu'al to expect from the activities 

 of the author, the mathematical point of view is especially emphasized, 

 but other phases of the subject are not neglected. 



The first chapter, A Critical Examination of Current Modes of 

 Research in Genetics, defines the problem and summarizes the meth- 

 odology of the subject. The similarity between members of the same 

 species, the importance of the germ cell, and the development and 

 differentiation of the individual, form the basis of the two conclusions 

 that there are various degrees of specificity of germinal substance, 

 and that reproductive processes tend to rffaintain this specificit5^ 

 Biometry, Mendelism, cytology and embr3'ology are each treated 

 clearly to show their essential characteristics and limitations as adapted 

 to genetics. These four are recognized as indirect methods of attack- 

 ing the question of heredity and a more direct method, through bio- 

 chemistry is suggested. In the next chapter a detailed discussion of 

 biometry clearly shows how widely this method of study has been 

 misunderstood both by its most ardent admirers and its enemies, arid 

 that the need of "qiiantification" is very great in the biological sciences. 

 Biometry offers primarily a method of describing a group as a group 

 instead of describing it by enumerating the characteristics of the lesser 

 units. It also clearly emphasizes the range of error in any set of 

 observations and gives a means of quantitatively correlating phenomena 



1 Pearl. Raymond, Modes of Research in Genetics. Pp. 182. New York, The 

 Miicinillnn Ci)nii):iny, 1915 ($1.2.5). 



