and where certain investigators have constructively helped to organize certain sec- 

 tions, specific acknowledgements are made. It is with pleasure that the author ack- 

 nowledges here the permission granted by The Wistar Institute of Anatoi^T' to reproduce 

 items from papers appearing in their various Journals. It must he emphasized again 

 that this book is made possible by the efforts of many experimental embryologists, 

 many deceased, many active, and an increasing number "presumptive". If biology stu- 

 dents who attempt these various procedures are thereby stimulated to make further con- 

 tributions to the field of experimental embryology, all the effort expended in its 

 compilation will have been justified. 



Roberts Rugh 

 New York 

 September 191*8 



