Vm CONTENTS 



OsTERHOUT, W. J. V. Antagonism between alkaloids and salts 



in relation to permeability 515 



DU NotJY, P. Lecomte. a new apparatus for measuring sur- 

 face tension 521 



Uhlenhuth, Eduard. Relation between metamorphosis and 



other developmental phenomena in amphibians 525 



Hecht, Selig. Sensory equilibrium and dark adaptation in 



Mya arenaria 545 



LoEB, Jacques. Amphoteric colloids. V. The influence of the 



Valency of anions upon the physical properties of gelatin. . . . 559 



No. 6, July 20, 1919. 



Crozier, W. J. Intracellular acidity in Valonia 581 



Crozeer, W. J. On the control of the response to shading in the 



branchige of Chromodoris 585 



Swingle, W. W. Iodine and the thyroid. III. The specific ac- 

 tion of iodine in accelerating amphibian metamorphosis .... 593 



Northrop, J. H. The effect of various acids on the digestion of 



proteins by pepsin 607 



Moore, A. R. The respiratory rate of the sciatic nerve of the 



frog in rest and activity 613 



Fred, E. B. The growth of higher plants in soils free of micro- 

 organisms 623 



Fred, E. B., and Haas, A. R. C. The etching of marble by roots 

 in the presence and absence of bacteria 631 



Morgan, T. H., and Bridges, Calvin B. The inheritance of a 



fluctuating character 639 



Bridges, Calvin B. Vermilion-deficiency 645 



Hecht, Selig. The nature of the latent period in the photic re- 

 sponse of Mya arenaria 657 



Hecht, Selig. The effect of temperature on the latent period in 



the photic response of Mya arenaria 667 



LoEB, Jacques. The physiological basis of morphological polar- 

 ity in regeneration. II 687 



LoEB, Jacques. The influence of electrolytes on the electrifica- 

 tion and the rate of diffusion of water through collodion 

 membranes 717 



