PREFACE 



I should like to express my appreciation to Dr. J. B. Collip, 

 Dr. H. Selye, Dr. D. L. Thomson, and Dr. W. J. Crozier for 

 their kindness in reading the manuscript of this book before 

 publication. Their comments have been taken advantage 

 of in a manner for which I, not they, am responsible. I am 

 indebted too to Dr. F. H. A. Marshall and Mr. John Ham- 

 mond of Cambridge University for encouragement and 

 interest which led to the undertaking of this monograph, 

 and to my friend and collaborator Dr. E. V. Enzmann who 

 actively assisted in a number of the investigations herein 

 described. The National Research Council Committee for 

 Problems of Sex and the Josiah Macy Jr. Foundation pro- 

 vided grants making possible most of my own work, and 

 the preparation of the monograph itself is due in no small 

 measure to their assistance. To the editors and publishers 

 of the following journals I am indebted for permission to 

 reprint the various tables and figures indicated in the text: 

 the American Journal of Anatomy, the American Journal 

 of Physiology, the Anatomical Record, Archives de Biologic, 

 the Biological Bulletin, the Carnegie Institution of Wash- 

 ington Publications in Embryology, the Journal of Anatomy, 

 the Journal of Experimental Biology, the Journal of Experi- 

 mental Medicine, the Journal of Experimental Zoology, the 

 Journal of Morphology, the Quarterly Review of Biology, 

 and the Proceedings of the Royal Society. 



I ask the understanding of the reader if this account of 

 the development of mammalian eggs seems at times to deal 

 in summary fashion with some of the voluminous literature 

 on this subject. The investigative aspects are what interest 

 and intrigue me. I emerge confessedly with the impression 

 that at best a qualitative basis for future work has been 

 estabhshed, and since I am possessed by the belief that 



