time is lost in looking for figures illustrating a particular structure or process. 

 A separate page index to tabular material would also have been very useful. 

 Another point of criticism concerns the way of indicating developmental age in 

 figure captions. For early stages it is often not clear whether the age given is 

 with respect to mating, ovulation, or fertilization. For later stages "days", "days 

 gestation", or "g.d." are used indiscriminately, and the latter abbreviation, which 

 apparently means "gestation days", is not explained. 



The book is concluded by a 51 -page glossary, a 45-page bibliography, and an 

 extensive subject index. The point of including a general embryological glossary 

 in a book of this kind is difficult to see. The bibliography is almost exclusively 

 concerned with the mouse, and is claimed to be nearly complete; however, English 

 titles predominate strongly. The bibliography is disfigured by numerous printing 

 errors; some of the German and French titles are altogether uninteHigible. 



Since in the text no reference is made to literature cited, the bibliography would 

 have gained greatly in usefulness by a subdivision following the table of contents. 



28 DIE ELEKTRONENMIKROSKOPISCHE STRUKTUR 



DER EIZELLE 



1967 



By H.-E. Stegner 



Ergebn. Anat. Entwickl.gesch. 



Band 39, Heft 6 



113 pp.. 53 figs., 1 tb. 



( paper-bound ) 



Springer- Verlag 

 Berlin - Heidelberg - New York 



The main topic of this monograph is the ultrastructure of the mammalian and 

 human oocyte, both in the mature state and during oogenesis. Other topics also 

 treated are ultrastructural aspects of the follicular apparatus, the egg membranes, 

 fertilization, cleavage, and the blastocyst prior to implantation. The monograph 

 is largely based on the author's own findings, but also covers the work of 

 numerous other authors, and thus serves as a guide to the literature. Wherever 

 this is clarifying, work on lower vertebrates and invertebrates is also discussed. 



There is a useful introductory section on techniques for preparing mammalian 

 eggs for electron microscopy. Most of the illustrations are well-reproduced 

 electron micrographs. The majority of these are original and refer to human, 

 rabbit, and mouse material. The work is concluded by an 18-page bibliography 

 and a subject index. 



29 



THE PLACENTA IN TWIN PREGNANCY 

 1967 



By S. J. Strong and G. Corney 

 134 pp., 52 figs., 9 pis., 16 tbs. 



Pergamon Press 



Oxford etc. 



Price: £ 6.2.0 



This book arose largely out of original research by the two authors. During 



their studies they became impressed by the fact that so much in the seemingly 

 settled subjects of twin conception, placentation, vascular relationships and zy- 



28 



