dependently as introductions to specific areas, particularly since cross ref- 

 erences to other relevant parts are given in footnotes throughout the book. 



Vol. 2 is in three parts, which deal respectively with gene action and 

 phenogenetics; allelic relations, environmental actions and gene interactions; 

 and biometrical methods and quantitative characters. 



It is particularly the first part that is of interest to developmental biologists. 

 It consists of two chapters, and occupies 220 pages. The first chapter, entitled 

 "Principles of gene action and phenogenesis; gene-controlled chemical reac- 

 tions", starts with a general discussion of gene action. 



Two newly coined terms play an important role in this discussion, viz. 

 "ergosis" and "treption". The first is a brief term for gene activation/in- 

 activation. The second term imphes chromosomal or genie changes other than 

 mutations, whether they be irreversible ("allotreption") or reversible ("eutrep- 

 tion"). Genie treptions play a role in cytodifferentiation; they are adaptive 

 and physiologically integrated, in contrast to mutations. The various bio- 

 chemical mechanisms which may be responsible for treption are extensively 

 discussed. The concept of treption considerably clarifies the discussions of 

 gene action. 



Other sections of particular interest in the first chapter are those dealing 

 with phenogenetics of eye pigmentation in insects and of hair pigmentation 

 in rodents. The second chapter of the first part is entitled "Cell differentiation 

 and the phenogenesis of form characters; pleiotropy and lethal effects". It 

 contains discussions of induced cell changes and differentiation, genetic control 

 of organ development in Drosophila (particularly eye and wing), pleiotropy, 

 lethal mutants, and homoeotic mutants. 



Of particular interest in the second part is a chapter entitled "Environmental 

 actions; phenocopies, teratogenesis and other effects of the environment" 

 (61 pp.)- Its concluding sections are devoted to the inheritance of acquired 

 characters. The next chapter has a long section on variability and stabihty of 

 gene effects, including a brief discussion of developmental homeostasis 

 (canalization). 



The book has a bibliograhpy of 44 pages in small print, in which the most 

 recent references are of 1963. The numerical literature reference system by 

 means of footnotes is commendable for other books. The illustrations are 

 numerous and adequate. The book is concluded by author and subject indexes. 



8 CYTOGENETICS 



1967 

 by C. P. Swanson, T. Merz and W. J. Young Prentice-Hall, Inc. 



Foundations of Modern Genetics Series Englewood Cliffs, N.J. 



208 pp., 93 figs., 10 tbs. Price: $ 3.25 



(paper-bound) 



Although this book was written primarily for the use of students, it is very 

 useful for a rapid orientation in the field of cytogenetics for non-specialists. 

 As is the case with the other books in this series, it presents the evidence on 

 which current thought is based. The treatment is selective, and emphasis is 

 placed on important questions which still require an answer. Wherever this is 

 clarifying, data from the field of molecular genetics are adduced. 



After a brief introductory chapter, the book opens with a chapter on the 

 architecture of the chromosome. The next chapter deals extensively with 

 meiosis, linkage and crossing over. Then follow three chapters dealing with 

 the sources and consequences of variation, as involving respectively chromo- 

 somal structure, chromosomal numbers, and variant chromosomal systems. The 

 book is concluded by a chapter entitled "The chromosome as a functional 

 organelle". 



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