BIOLOGICAL BULLETIN 



OF THE 



fiDarine iolo$ical laboratory 



WOODS HOLE, MASS. 



Editorial Staff 



E. G. CONKLIN Princeton University. 



GEORGE T. MOORE The Missouri Botanic Garden. 



T. H. MORGAN Columbia University. 



W. M. WHEELER Harvard University. 



E. B. WILSON Columbia University. 



Managing Efcitor 



FRANK R. LILLIE The University of Chicago. 



VOLUME XXXIX. 



WOODS HOLE, MASS. 

 JULY TO DECEMBER, 1920 



