THE 



COURSE OF EVOLUTION 



BY DIFFERENTIATION OR 

 DIVERGENT MUTATION RATHER THAN 



BY SELECTION 



by 



J. C. WILLIS 



M.A., Sc.D., Hon. Sc.D. (Harvard), F.R.S. 



European Correspondent, late Director, Botanic 

 Gardens, Rio de Janeiro 



CAMBRIDGE 



AT THE UNIVERSITY PRESS 



1940 



