IV CONTENTS 



Alvalyn E. Woodward. Studies on the physiological significance of cer- 

 tain precipitates from the egg secretions of Arbacia and Asterias. Two 

 charts and three figures 459 



S. O. Mast. Effects of chemicals on reversion in orientation to light in the 



colonial form, Spondylomorum quaternarium 503 



A. Franklin Shull. Relative effectiveness of food, oxygen, and other sub- 

 stances in causing or preventing male-production in Hydatina 521 



Shinichi Matsumoto. Contribution to the study of epithelium movement. 



The corneal epithelium of the frog in tissue culture. Nine figures 545 



