The scope of most contributions is wider than the volume ti- 

 tle suggests, and they will be read with profit by all those 

 interested in chromosome structure and function, and in eukaryo- 

 tic gene regulation generally. Contribution 1 has some striking 

 electron micrographs of Drosophila chromosomes, while contribu- 

 tion 6 devotes attention to the strict parallellism between 

 puffing activity and cellular differentiation in "Kleinorgane" , 

 the latter illustrated with electron and Nomarski interference 

 micrographs . 



The book is beautifully produced and illustrated, but one 

 wonders whether the luxurious production and the concomitant 

 high price were really necessary, particularly in view of the 

 absence of indexes. 



119. 



B.EPHRUSSI. 1972. HYBRIDIZATION OF SOMATIC CELLS 



Princeton Univ. Press, Princeton. XII, 175 pp., 35 figs., 14 



tabs., author and subject indexes. £ 4.75, $ 9.50 (cloth); 



£ 2.50, $ 4.95 (paper) 



This stimulating monograph is based on the text of three lec- 

 tures given at Princeton University in January, 1971. The text 

 has been somewhat extended and updated and 30 pages of notes 

 were added, but the treatment is still highly selective. The 

 resulting brevity makes the book very suitable for rapid orien- 

 tation in this fascinating field, particularly for developmental 

 biologists, because the author's main interest has always been 

 in problems of cell differentiation. The book has a distinctly 

 personal flavour; much attention is devoted to theoretical im- 

 plications . 



The author was one of the pioneers in this area since it was 

 opened up in I960. The first chapter presents an introduction 

 into the principles of the cell fusion technique in the form of 

 an historical account. The bulk of the book deals with its ap- 

 plication to three areas of research: human genetics, cell dif- 

 ferentiation, and cancer. The second area takes up almost half 

 of the main text, i.e. three chapters, two of which bear the 

 subtitles Reactivation of nuclei of differentiated cells in 

 heterokaryons , and The fate of luxury functions in somatic hy- 

 brids. In the latter the main theoretical preoccupation is with 

 the stability of the determined (epigenetic) state of cells in 

 vitro. The other two areas mentioned are treated much more 

 briefly, that of cancer again chiefly in view of its possible 

 implications for normal development. In bis concluding remarks 

 the author touches upon much broader theoretical problems, such 

 as the possible role of the cell membrane in differentiation 

 and the cell theory generally. 



The book is attractively produced and well illustrated. 



120. 



G.JAGERSTEN. 1972. EVOLUTION OF THE METAZOAN LIFE CYCLE, a com- 

 prehensive theory 



Academic Press, London, etc. X,282 pp., 59 figs., author and 

 subject indexes. £ 5.00, $ 15.50 



This book is essentially a translation of a book first pub- 

 lished in Swedish in 1968. It contains a new, comprehensive (but 

 somewhat controversial) theory of metazoan evolution which has 

 its starting point in the author's "bilaterogastraea" theory 

 first expounded in 1955. Since then the author has carried out 

 a number of necessary supplementary studies which are incorpo- 

 rated into this text. The central thesis of the new theory is 



233 



