PRINCIPLES OF 



BY 



JOSEPH Y. BERGEN, A.M. 



AUTHOR OF "ELEMENTS OF BOTANY," "FOUNDATIONS OF BOTANY,' 

 " PRIMER OF DARWINISM," ETC. 



BRADLEY M. DAVIS, PH.D. 



HEAD OF DEPARTMENT OF BOTANY IN THE MARINE BIOLOGICAL, 



LABORATORY, RECENTLY ASSISTANT PROFESSOR OF PLANT 



MORPHOLOGY IN THE UNIVERSITY OF CHICAGO 



GINN & COMPANY 



BOSTON NEAV YORK CHICAGO LONDON 



