161 



This does not hold only for courses for premedical students or first year stu- 

 dents in biology, but just as well for more advanced students who like to get 

 a more detailed picture of the development of the frog and chick which forms 

 are treated very extensively. Even instructors and teachers in biology may 

 use the accurate and many sided information which this manual gives. 



The development of some invertebrate eggs with their different types of 

 cleavage and the more extensive description of the development of Amphioxus 

 form a good introduction. 



The fish development in the form of the development of the egg of Oryzias 

 latipes — which seems to be an excellent laboratory animal — could, in our 

 opinion, have shown to better advantage when the drawings would have been 

 larger and more detailed. The photographs which do not show very well, could 

 probably have been omitted. Students can even use this material for practical 

 study. 



The embryology of the frog has been treated very thoroughly and accu- 

 rately and forms the basis for an understanding of and a comparison with the 

 development of the higher Vertebrates. Since the experimental embryology has 

 been mainly studied on Urodeles, a short comparative sketch of the deve- 

 lopment of Ambystoma or Triturus might have formed a very worthful exten- 

 sion of the text. A similar suggestion can be made concerning the development 

 of the reptilian egg where a short description adorned with some illustrations 

 would have completed the general picture of vertebrate development. This is 

 the more important since so many textbooks give the impression that verte- 

 brate development is identical with the development of frog, chick and pig. 



The development of the chick is very comprehensive and illustrative. The 

 formation and regression of the primitive streak so clearly visible in the chick 

 might, however, have been treated somewhat more in detail. The normal table 

 of the somite stages of the chick forms a good and surveyable source of 

 information for the student. 



Although the chapter on mammalian development forms only a comparative 

 sketch to the extensive chapters on chick development the text of the early 

 mammalian development is, in our opinion, somewhat summary while also the 

 human development could have been described and illustrated somewhat more 

 richly. 



These suggestions for an extension of the text will not necessarily lead to 

 an extension of the practical laboratory course but will, in our opinion, make 

 this manual of vertebrate development much more universal and useful. 



P. D. NIEUWKOOP. 



„THE EPIGENETICS OF BIRDS" 



1952 



by C. H. Waddington Cambridge University Press 



268 pages with 70 figures 



This new book gives a comprehensive survey of our recent state of know- 

 ledge in the causal analysis of the early development of birds. After a dis- 

 cussion of the various technical methods developed for experimental analysis 

 in birds — among which the in vitro cultivation developed by the author and 

 his coworkers — the early development with its fundamental problems 

 concerning the segregation of the blastoderm into distinct germ layers, the 

 formation and regression of the primitive streak and the interactions between 

 the various germ layers in the four-dimensional process of organization and 



