IV CONTENTS 



LoRANDE Loss WooDRUFF. MicFonucleate and amicronucleate races of 



Infusoria. Four figures 329 



HoYT S. Hopkins. The conditions for conjugation in diverse races of Para- 

 mecium : 339 



John H. Gerould. Blue-green caterpillars: the origin and ecology of a 

 mutation in hemolymph color in Colias (Eurymus) philodice. One text 

 figure and one colored plate (six figures) 385 



L. V. Heilbrunn. Protoplasmic viscosity changes during mitosis. One 



chart 417 



Gary N. Calkins. Uroleptus mobilis Engelm. IV. Effect of cutting 



during conjugation. Ten figures 449 



E. J. Lund. Experimental control of organic polarity by the electric cur- 

 rent. I. Effects of the electric current on regenerating internodes of 

 Obelia commissuralis. Three figures and three double plates 471 



