162 



segregation, has been extensively discussed. A comparison with the causal 

 analysis of the early development in Amphibians demonstrates clearly how far 

 the development. in both groups of Vertebrates goes parallel, and in what res- 

 pects other mechanisms are involved. Moreover it shows to what point the 

 analysis in both groups has led up till now. Since the analysis has been mainly 

 based upon in vitro experiment under which conditions a normal development is 

 not entirely guaranteed, the more general features and problems could be studied 

 whereas the finer organization and differentiation could not be investigated 

 very accurately. Processes of growth which are normally already involved in 

 the early organogenesis, but which are absent under these experimental con- 

 ditions, are only briefly mentioned. The biochemical aspects of morphogenesis 

 have also been discussed in extenso. The development of the various organ 

 systems which are reviewed systematically, is less comprehensive than the 

 analysis in both groups has led up till now. Since the analysis has been mainly 

 ing for so many years. Nevertheless, it briefly treats nearly all the experi- 

 mental literature on this later phase of development. 



As the author mentions in his introduction the main problem was where 

 to stop. We are not quite sure that he has already found the most adequate 

 hmitation of the field treated. The later chapters on plumage and genetic 

 effects in development have a rather fragmentary character. It might have 

 been better to omit these chapters and to discuss the development of the 

 various organ systems more extensively. 



The last chapter on the epigenetic organization of the chick which a.o. 

 gives the author's point of view upon this central problem, is of great theore- 

 tical importance and forms a very good conclusion of this book. 



The references of the literature are accurate and very extensive so that 

 this clearly written book actually gives us a general survey of the literature 

 in the field of the epigenetics of birds. 



Except for a few diagrams which are somewhat too schematic, the illustra- 

 tions are very well chosen and excellently reproduced. 



Although the author refers more than once to the existing normal tables on 

 the development of the chick, an introduction on normal development, freely 

 illustrated, would certainly have facilitated the reading of the experimental 

 chapters, especially for those not directly familiar with bird development. 



This purely scientific book really meets a general want and will be highly 

 appreciated among embryologists. 



P. D. NIEUWKOOP 



.,AN INTRODUCTION TO VERTEBRATE EMBRYOLOGY" 



Second Edition, 1949 

 by H. L. Wieman Mc Graw-Hill Book Company, Inc. 



New- York - Toronto - London 

 404 pages with 247 figures 



This textbook, designed for introducing the premedical student in the 

 embryology of the Vertebrates, gives first some general aspects of develop- 

 ment. The chapter on gametogenesis is treated rather extensively. Except for 

 some minor details an accurate survey is given of the development of the 

 frog. The more extensive treatment of the development of the frog in this 

 second edition certainly forms an improvement. The development of the 

 chick is likewise treated with accuracy and thoroughness. Unfortu- 

 nately the fundamental processes of gastrulation in the frog and 



