BIOLOGICAL BULLETIN 



OF THE 



flTmrine Biological 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 ]fcitor 



FRANK R. LILLIE -The University of Chicago. 



VOLUME XL. 



WOODS HOLE, MASS. 

 JANUARY TO JUNE, 1921 



