BIOLOGICAL BULLETIN 



OF THE 



fiOarinc Kiolocjical Xaborator^ 



WOODS HOLL, MASS. 



Editorial Staff 



E. G. CONKLIN The University of Pennsylvania. 

 JACQUES LOEB The University of California. 

 T. H. MORGAN Columbia University. 

 W '. M. WHEELER American Museum of Natural 



History, New York. 



C. O. WHITMAN The University of Chicago. 

 E. B. WILSON Columbia University. 



FRANK R. LILLIE The University of Chicago. 



VOLUME XII. 



WOODS HOLL, MASS. 

 DECEMBER, 1906, TO MAY, 1907. 



