G. LEDYARD STEBBINS is Chairman 

 of the Department of Genetics at the Uni- 

 versity of California at Davis, where he 

 devotes a major part of his time to study 

 of the evolutionary dynamics of plants. 

 Among his publications, the book, Vari- 

 ation and Evolution in Plants, has been 

 especially widely acclaimed. Professor 

 Stebbins is a member of the National 

 Academy of Sciences and the American 

 Philosophical Society. 



