It is impossible to review the 16 short chapters in detail. The author 

 discusses the ontogeny of about 70 regulated activities, mostly in fetal and 

 postnatal mammals, including man. The regulation of heart rate (pacemaker) 

 serves as a model, on the basis of which other types of regulation are 

 expounded. The dichotomy between programmed and triggered events is 

 emphasized, as is that between intrinsic and extrinsic regulation. One chapter 

 discusses the ontogeny of behaviour as a component of regulation. Another 

 deals with comparisons between species as regards sequences of maturation. 



The book is very well produced; it is illustrated mainly with diagrams 

 and graphs, and is concluded by a subject index. 



24 ULTRASTRUCTURE OF FERTILIZATION 



1968 



By C. R. Austin Holt, Rinehart and Winston 



Biology Studies Series New York - London 



196 pp., 79 figs. Price: 56 s. 



Although this book, written by an outstanding expert in the field, belongs 

 to a series intended for students, it should be equally useful to research 

 workers, particularly since it provides detailed procedural data. This is done 

 by way of a separate chapter in which some 80 publications are listed with 

 details of electron microscopic procedures used. 



The main text is organized into five chapters, the first four of which deal 

 respectively with sperm penetration through egg investments, fusion of con- 

 jugants and gametes, reactions of eggs to sperm penetration, and nuclear 

 migration, development, and union. Each of these four chapters opens with 

 a brief section providing the necessary biological background. The last 

 chapter of the main text is a brief general discussion. Throughout the book 

 material is drawn from both the animal and plant kingdoms. Much attention 

 is devoted to problems of terminology. 



In a book like this the illustrations are obviously of the greatest importance. 

 Considering that they are printed on ordinary paper, it is surprising how 

 well they have come out. Some very good line drawings are also included. 

 The book has a 13-page bibhography and is concluded by author and subject 

 indexes. Its price seems excessive. 



25 THE EVOLUTION OF DIFFERENTIATION 



1967 



By W. S. Bullough Academic Press 



206 pp., 32 figs. London - New York 



Price: $ 9.50; 45 s. 



Contents: 1. Introduction; 2. The simplest living organisms: bacteria; 3. Unicellular plants 

 and animals; 4. Tissue and organ formation; 5. Tissue homeostasis; mass and function; 6. Tissue 

 homeostasis: hormones; 7. Carcinogenesis; 8. Summary 



This essay is a successful attempt to synthetise a wealth of recent data 

 bearing on differentiation and gene control. The author has worked for 

 several decades on problems of mitotic control in mammalian tissues, and, 

 incidentally, views mitosis as a special case of differentiation. 



The information reviewed ranges from the more labile chemical control of 

 the genetic mechanisms of unicellular organisms to the chemical control of 

 more stable differentiation in multicellular organisms, both during embryonic 

 development and in the adult state (including ageing). A final chapter deals 

 with the cancer problem. The final conclusion of the book is that the 

 "evolution of cellular differentiation, dramatic as its consequences have been, 

 has involved nothing more than an increasing elaboration of an ancient 



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