meaningful and the most hopeful experimentally. However, it will also appear 

 that at present many of the links between each level of the subject are exceed- 

 ingly tenuous and it is one of the objects of this book to reveal these defi- 

 ciencies. But by using this approach it will be shown that a great deal of the 

 conjecture which the subject has collected is redundant." 



The last chapter of the book, which is also the longest (84 pp.), is perhaps of 

 most immediate interest to embryologists. It contains, among other things, sections 

 on fertilization, blastulation, gastrulation, neurulation, the neural crest, mesoderm 

 cell movements, and patterning of cell contacts in the nervous system (including 

 regeneration of neural connections). 



We must be thankful to the author for presenting such a wealth of data in a 

 coherent and very readable account, and also for the way in which he constantly 

 points up the many areas in which solid experimental data are still lacking. 



The text-figures are restricted to clear diagrams; all the plates are electron 

 micrographs. The bibliography numbers 45 pages and is made entirely up to date 

 in a brief addendum. The book is concluded by an extensive subject index. 



21 activite des Genes 



AU COURS DU DeVELOPPEMENT embryonnaire 



1966 



By H. Denis Desoer-Editions 



144 pp., 61 figs., 13 tbs. Liege 



(paper-bound) Price: B.F. 180 



This monograph reports on original research carried out by the author over a 

 number of years, which has aot been published in full in the form of journal 

 articles. The work was carri^id out in the Laboratory of Animal Morphology, 

 Brussels (Prof. Brachet) and at the Department of Embryology, Carnegie 

 Institution, Baltimore (Prof. Ebert). 



The monograph is in two parts. Part one ("Influence of actinomycin on em- 

 bryonic development", work carried out in Brussels) deals with the influence of 

 actinomycin on the synthesis of nucleic acids and proteins, and on the competence 

 of the ectoderm and the inductive capacity of the blastoporal lip. All this work 

 was done on embryos of Plemodeles waltlii. Part two ("Liberation of genetic 

 information during embryonic development") describes work carried out in 

 Baltimore, using molecular hybridization techniques on Xenopus laevis material. 

 An extensive discussion of the techniques used is followed by an expose of the 

 results obtained on the properties and types of messenger RNA synthesized by 

 the embryo at successive stages. 



As J. Brachet points out in his laudative preface to the monograph, the results 

 presented here are very original and will form the basis for the forthcoming 

 molecular attack of many important problems of embryology, e.g. preformation 

 vs. epigenesis, role of cytoplasmic localizations, type of information transfer in- 

 volved in cleavage, morphogenetic movements, induction etc. 



The book is illustrated with numerous photographs and graphs. It has no 

 subject index, but a very detailed table of contents partly compensating for this 

 lack. 



23 



