

ANALYSIS OF 

 DEVELOPMENT 



EDITED BY 



BENJAMIN H. WILLIER 



Professor of Zoology, Johns Hopkins University, Baltimore, Maryland 



PAUL A. WEISS 



Member, Rockefeller Institute for Medical Research, New York, New York; 

 formerly Professor of Zoology, University of Chicago, Chicago, Illinois 



VIKTOR HAMBURGER 



Professor of Zoology, Washington University, St. Louis, Missouri 



ILLUSTRATED 



W. B. SAUNDERS COMPANY 



Philadelphia & London • 1955 



