S AUTHOR S PREFACE TO THE FIRST EDITION. 



I have, it is true, employed chiefly as the foundation of my pre 

 sentation the views which appear to me the most entitled to 

 acceptance, but have not left un mentioned opposing conceptions. 



Numerous figures in the text, as well as some colored plates, will 

 contribute materially to the easier comprehension of the various 

 developmental processes. 



I submit, then, this text-book to physicians and to students of 

 medicine and the natural sciences, with the desire that it may 

 promote and facilitate the study of Embryology in wider circles, and 

 that it may thereby contribute to a deeper insight into the structure 

 of our own bodies. 



OSCAR HERTWIG. 

 JENA, October 1886. 



