HOW ANIMALS DEVELOP 



New material Copyright @ 1962 

 by C. H. Waddington 

 Printed in the United States of America 

 This book was originally published in 1935 by 

 Allen lb- Unwin, Ltd., London and is reprinted 

 by arrangement. A new last section, "The Ac- 

 tivity of Genes in Development" has been writ- 

 ten by Dr. Waddington. 

 First HARPER TORCHBOOK edition published 1962 



