PREFACE 



THIS book represents an attempt to combine brief descriptions of the verte- 

 brate embryos which are studied in the laboratory with an account of human 

 embryology adapted especially to the medical student. Professor Charles Sedg- 

 wick Minot, in his laboratory textbook of embryology, has called attention to the 

 value of dissections in studying mammalian embryos and asserts that "dissection 

 should be more extensively practised than is at present usual in embryological 



work ." The writer has for several years experimented with 



methods of dissecting pig embryos, and his results form a part of this book. The 

 value of pig embryos for laboratory study was first emphasized by Professor Minot, 

 and the development of my dissecting methods was made possible through the 

 reconstructions of his former students, Dr. F. T. Lewis and Dr. F. W. Thyng. 



The chapters on human organogenesis were partly based on Keibel and 

 Mall's Human Embryology. We wish to acknowledge the courtesy of the pub- 

 lishers of Kollmann's Handatlas, Marshall's Embryology, Lewis-Stohr's Histology 

 and McMurrich's Development of the Human Body, by whom permission was 

 granted us to use cuts and figures from these texts. We are also indebted to 

 Professor J. C. Heisler for permission to use cuts from his Embryology, and to 

 Dr. J. B. De Lee for several figures taken from his "Principles and Practice of 

 Obstetrics." The original figures of chick, pig and human embryos are from 

 preparations in the collection of the anatomical laboratory of the Northwestern 

 University Medical School. My thanks are due to Dr. H. C. Tracy for the loan 

 of valuable human material, and also to Mr. K. L. Vehe for several reconstruc- 

 tions and drawings. 



C. W. PRENTISS. 



NORTHWESTERN UNIVERSITY MEDICAL SCHOOL. 



