UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 20, No. 8, pp. 199-234, plates 23-26, 1 1 figures in text March 7, 1922 



MITOSIS AND FISSION IN THE ACTIVE AND 

 ENCYSTED PHASES OF GIARDIA ENTERICA 

 (GRASSI) OF MAN, WITH A DISCUSSION OF 

 THE METHOD OF ORIGIN OF BILATERAL 

 SYMMETRY IN THE POLYMASTIGOTE 

 FLAGELLATES 



BY 



CHARLES A. KOFOID AND OLIVE SWEZY 



UNIVERSITY OF CALIFORNIA PRESS 

 BERKELEY, CALIFORNIA 



