BOOKS AND CURRENT LITERATURE 245 



which are not necessarily related in the chain of cause and effect. 

 The limitations of biometry are shown to be largely those of a de- 

 scriptive method. The Nature of Statistical Knowledge is next 

 discussed, illustrated by specific examples and with the conclusions 

 that while the description of a group, as accomplished by statistical 

 methods, is a ver}' proper and valuable asset in biological work, on the 

 other hand the prediction of the conditions of the individual, from the 

 data concerning the group, is only an aid to, and not a substitute for, 

 other methods of study of the individual. The problem of inbreeding 

 is discussed in detail particularly emphasizing a "method of measur- 

 ing the intensity or degree of the inbreeding practiced in any partic- 

 ular case." A "coefficient of relationship" is proposed and illustrated 

 with definite examples, and the consequences of inbreeding, considered 

 as a genetic problem, are discussed. The final chapter of the book 

 shows the practical progress which animal breeding has made inde- 

 pendently of genetics, and largely before that science came into exist- 

 ence. However, genetics is of value to the practical breeder in spite 

 of his relatively great progress through empirical methods. Progress 

 in plant breeding has been greatly stimulated, especially by the stud}' 

 of MendeUsm, l^ecause the plant breeder is unhampered by the re- 

 strictions of "pure breed" registering and the attendant difficulties of 

 placing new breeds before the world upon their own merits. 



From this short review of the contents of the book it will be seen 

 that wliile some parts are written particularly for investigators in 

 genetics, parts, at least, are of great interest to the general reader 

 and especially to those engaged in other phases of biological work. 

 The book, as a collection of rather independent essays, is less unified 

 and more unequal in scientific detail than one might desire for a general 

 review of the subject, but it is, nevertheless, a stimulating, critical 

 summary which justified its title. — Ernest Shaw Reynolds. 



