29 



altogether missing. The second part of the book is a synthesis of the data 

 described, illustrated with numerous original diagrams. It also deals with the 

 genetical consequences of the various meiotic aberrations combined with 

 parthenogenesis. 



Among the numerous species treated in the book are representatives of the 

 Plathelminths, Nematodes, Oligochaets, Rotifers, Molluscs, Crustaceans, and 

 Insects. 



The book is illustrated with numerous figures which are partly taken directly 

 from the literature, and partly carefully redrawn. The book is concluded by a 

 bibliography and a list of genera and species. 



21. PREGASTRULATIE EN GASTRULATIE DER VOGELKIEM 

 morfologische en experimentele studie 

 (Pregastrulation and gastrulation in the avian embryo, 

 a morphological and experimental study) 

 1962 

 by L. Vakaet Arscia Uitg. N.V. 



244 pp., 54 figs., 12 tbs. Brussel 



This monograph, written in Dutch, embodies the results of the authors 

 extensive re-investigation of pregastrulation and gastrulation in the avian 

 embryo. The work was carried out mainly on chick and duck material in stages 

 ranging from before the appearance of the area opaca till the oldest pre-somite 

 stage. An original series of stages was established which is more detailed than 

 that of Hamburger and Hamilton. 



The results fall into three categories, viz. 1 ) Histological and histochemical 

 observations; 2) Observations in viv o with or without vital staining; 3) Experi- 

 mental investigations in ovo (splitting of the blastoderm in various ways) and 

 in vitro (culture of isolated germ layers, culture of germ layers rotated with 

 respect to one another, culture of fragments of the blastoderm and the primitive 

 streak). There is an extensive discussion, in which the concept of "morpho- 

 genetic potential" (Dalcq and Pasteels) plays an important role, and in which 

 presumptive maps are proposed for the various stages which differ rather 

 much from the ones that are currently accepted. 



The work is concluded by rather brief summaries in Dutch, French, and 

 English. It is illustrated with line drawings and photomicrographs. 



Without wishing to debase his own mother tongue, the reviewer is inclined to regret that 

 this work, which is certainly of interest to many workers who cannot read Dutch, has not 

 been written in one of the congress languages. It is to be hoped that a translation will appear 

 soon. 



22. THE CYTOPLASM IN HEREDITY 



1964 



by D. Wilkie London: Methuen & Co Ltd. 



Methuen's Monographs New York: John Wiley & Sons Inc. 

 on Biological Subjects Price: 16 s. 



115 pp., 18 figs. 



So far an up-to-date synthetic account of cytoplasmic inheritance and its 



