Author's Preface. 



It is only owing to my esteemed friend, Dr. F. H. A. Marshall, 

 who has contributed so much to our knowledge of the internal 

 secretion of the ovary, that it was possible for me to publish 

 this book. Dr. Marshall has kindly corrected my foreign 

 EngUsh throughout the whole manuscript and afterwards read 

 the proofs. May I be permitted here to express my sincere 

 gratitude to Dr. Marshall, who has done all this hard work in 

 the most unselfish manner. 



It was originally intended to publish a revised translation 

 only of my book Die Puhertdtsdruse und ihre Wirkungen 

 (Berne, 1919). But when I began translating the book, to- 

 gether with my friend Dr. Karl Kautsky jun. in Vienna, who 

 had undertaken to translate part of it, it became clear to me 

 that the book had to be entirely rewritten. Since 19 18 im- 

 portant experimental work has been done in this special field 

 of physiology. To the foundation laid by Bouin and Ancel, by 

 Steinach and by Tandler, facts have been added which have 

 enriched our knowledge on the internal secretions of the sex 

 glands and on their bearing on morphogenesis in an extra- 

 ordinary manner. I mention only the important work done 

 by Goodale and by Pezard in fowls and the quantitative investi- 

 gations of the latter in the laboratory of Gley; the remark- 

 able work done by Sand in mammals, especially on herma- 

 phroditism; the experiments of Zawadowsky, who confirmed 

 and richly enlarged the statements of Goodale and Pezard; 

 the most interesting observations of Lillie and his pupils and 

 those of Tandler and Keller on the freemartin; the work of 

 Marshall and his co-workers, of Morgan, of Pearl, of Crew, 

 of Athias, Harms and Wilhelm. Bouin and his pupils, and 

 Champy, Guyenot and Kolmer have extended the problem 

 to a great many species. Goldschmidt has given knowledge 

 of unexpected facts on insects. Some of these new investi- 

 gations have been shortly mentioned already in the first 

 edition, but most of them were published only in the last five 

 years. My point of view has been widely influenced also by 

 the result of my own experimental work done during the last 

 five years in this Institute. So a new book originated from 

 the old one. 



