/y. 



W.NAGL. 1978. ENDOPOLYPLOIDY AND POLYTENY IN DIFFERENTIATION AND EVOLUTION; 

 towards an understanding of quantitative and qualitative variation of nuclear 

 DNA in ontogeny and phylogeny 



North-Holland, Amsterdam, etc. XIV, 283 pp., 154 figs., 26 tabs., combined 

 taxonomic and subject indexes. $ 54.50, Df 1.125.00 



Contents: 1. Organization of the eukaryotic chromosome, 2. Occurrence and 

 characterization of endopolyploid nuclei, 3. Mechanisms of endopolyploidi- 

 zation, 4. Further mechanisms of nuclear DNA variation, 5, Control of en- 

 ■ dopolyploidization and polytenization, 6. Functional significance of endo- 

 cycles, 7. Evolutionary aspects 



The main value of this book for our readers lies in the fact that it brings 

 together a mass of data from both animals and plants showing that endopoly- 

 ploidy is a much less exceptional phenomenon than many biologists think. I 

 quote from Chapter One: "It is one of the chief intentions of the present 

 work to demonstrate that the nucleus and its DNA and chromatin exhibit a 

 dynamic organization rather than a constant one. The collection of data on 

 endopolyploidy and differential DNA replication may show that most cells of 

 most organisms do have quantitatively and qualitatively different DNAs in 

 their nuclei. The extensive review of the data offers the chance to under- 

 stand developmental variation of DNA and chromatin as an important factor in 

 gene regulation and cell differentiation". The author feels that this DNA 

 variation is involved both in the characteristic form and function of a 

 species and in its realisation during development. 



The table of contents above speaks for itself. In ch.6 most of the exper- 

 imental evidence cited derives from insect and particularly plant studies 

 (many of them by the author and his associates). At the end of ch.7 the 

 author presents a "DNA optimisation model" to account for some relationships 

 between nuclear DNA variation during ontogenesis, anagenesis and cladogenesis . 

 He ends by expressing support for a recent statement by Britten and David- 

 son's group to the effect that "divergence during phylogenesis and ontogene- 

 sis are two sides of the same coin, or, in other words, speciation and dif- 

 ferentiation are two sides of DNA variation". 



The book is concluded by a glossary and a guide to the literature pertain- 

 ing to methods (molecular-biological and otherwise) . The bibliography runs 

 into 1977 and covers 50 pages of small print. The book is beautifully pro- 

 duced and superbly illustrated. 



A.NESSI de AVINON. 1977. LAS CE!luLAS ROJAS; fundamentos bio-f isiologicos de 

 la eritropoyesis (The red blood cells; bio-physiological foundations of ery- 

 thropoiesis) (in Spanish) 

 Celcius, Buenos Aires. 169 pp., 51 figs., 5 tabs. 



Contents (translated): 1. Mechanisms of differentiation, 2. Specific pro- 

 teins, 3. The red cell series, 4. The hemopoietic stem cell, 5. Hemopoietic 

 organs, 6. Erythropoietin, 7. The ery thro-inhibitory factor 



Modern treatment of the subject in the framework of developmental biology 

 (chs.l and 2); brief introduction on homeostatic laws and cell populations; 

 emphasis on cell interactions; literature largely up to 1973, occasionally 

 later; illustrated with diagrams and micrographs. 



216 



