264 



The Journal of Heredity 



dealing with pouUr}- where the chromo- 

 some situation is not clear, and it will 

 be welcomed by those i)ersons, who 

 being unfamiliar with genetic theory 

 and terminology, react to the word 

 chromosome as a bull to a red flag. It 

 is neverdieless a serious omission in a 

 survey of any genetic subject. 



The chief contributions of the book 

 to a summary of progress in poultry 

 genetics are in the chapters on plumage 

 color and structural features, and in 

 the bibliography of one hundred and 

 forty-eight titles. This work of sum- 

 mary was much needed, and Professor 

 Punnett has probably accomplished all 

 that can l)e done at the present time. 

 He has emphasized the incomplete state 

 of our knowledge and the opportunity 

 and need for further research, and this 

 is generally the chief value of a sum- 

 mary of progress in science. In the 

 text are also added numerous valuable 

 observations of the author which had 

 not been published previously, and 

 which now become a part of the litera- 

 ture of the subject. 



In the short readal)le treatment of 

 the subject which Professor Punnett 

 has given, omissions and simplifications 

 are to the advantage of the reader not 

 versed in genetics. The all inclusive 

 and detailed nature of many books on 

 scientific subjects is often the feature 

 which restricts their appeal to purely 

 professional readers. Without ap- 

 pearing to "write down" to the ama- 

 teur. Professor Punnett has provided 

 him with an introduction and a guide, 

 while the annotated references will 

 send him, if he is interested, to the 

 original data. The geneticist will find 

 few specific criticisms to make. One 

 which will appear is the confusion of 

 "sex-linked" and "sex-limited" traits 

 (Cf Esp. [). TS). This distinction which 

 has become fixed in American litera- 

 ture, is not clear either in this volume 



or in the author's previous book, 

 "Mendelism." Chapter VI, on second- 

 ary sexual characters appears to suffer 

 from this lack of clarity and from a 

 rather controversial discussion of the 

 author's hypothesis of the inheritance 

 of hen feathering. The hypothesis in- 

 cludes identification of a factor having 

 the mode of transmission assumed for 

 the "W" chromosome {vis, from moth- 

 er to daughter), with the secondary 

 sexual secretion of the ovary. This 

 material does not seem to be on a pari- 

 ty with the rest of the book. 



Breeders of Barred Plymouth 

 Rock fowls for exhibition will proba- 

 bly question his statement (p. 128) 

 that "the show cock is usually heter- 

 ozygous in the barring factor," while 

 the homozygous cock is too light for 

 exhibition. Evidence in support of this 

 contention is lacking so far as the 

 writer knows. The reason for using 

 the "double mating" system by which 

 Barred males and Barred females for 

 show are produced from separate mat- 

 ings, is not to prevent the production 

 of black females by the exhibition type 

 of cock, but to increase the darkness 

 of the male oft"spring by breeding from 

 females which are darker than the 

 standard shade, and in such matings 

 standard type males are used success- 

 fully by both American and English 

 breeders. 



Biologists will welcome this book and 

 need have no hesitation in recommend- 

 ing it to their poultrymen friends. 

 With the growing interest of poultry- 

 men in the principles of inheritance, it 

 should have a wide sale, and could be 

 put to good use as a text in a poultry 

 course devoted to breeding. 



It is tuiiform in format with the 

 author's "Mendelism," and exhibits the 

 same high quality of composition and 

 press-work. 



L. C. Dunn. 



