CONTENTS VI 1 



LoEB, Jacques. Influence of the concentration of electrolytes 



on some physical properties of colloids and of crystalloids. . 273 

 LoEB, Jacques. Quantitative laws in regeneration. 1 297 



No, 4, March 20, 1920. 



Northrop, John H. A device for regulating the temperature 



of incubators either above or below room temperature 309 



Northrop, John H. Concerning the hereditary adaptation of 



organisms to higher temperature 313 



Moore, A. R. Stereotropism as a function of neuromuscular 



organization 319 



Uhlenhuth, Eduard. Regeneration and neoteny 325 



Brooks, Matilda Moldenhauer. Comparative studies on 

 respiration. X. Toxic and antagonistic effects of mag- 

 nesium in relation to the respiration of Bacillus suUilis 331 



Hecht, Selig. Intensity and the process of photoreception . . . 337 



Maxwell, S. S. Labyrinth and equilibrium. II. The mechan- 

 ism of the dynamic functions of the labyrinth 349 



Carey, Eben J. Studies in the dynamics of histogenesis. I. 



Tension of differential growth as a stimulus to myogenesis. 357 



LoEB, Jacques. The nature of the directive influence of gravity 



on the arrangement of organs in regeneration 373 



LoEB, Jacques. On the cause of the influence of ions on the 



rate of diffusion of water through collodion membranes. I. 387 



Krafka, Joseph, Jr. The effect of temperature upon facet 



number in the bar-eyed mutant of Drosophila. Part I . . . . 409 



No. 5, May 20, 1920. 



Krafka, Joseph, Jr. The effect of temperature upon facet 



number in the bar-eyed mutant of Drosophila. Part II. . . 433 



Kraeka, Joseph, Jr. The effect of temperature upon facet 



number in the bar-eyed mutant of Drosophila. Part III. . . 445 



Northrop, John H. The influence of hydrogen ion concentra- 

 tion on the inactivation of pepsin solutions 465 



Northrop, John H. The effect of the concentration of enzyme 



on the rate of digestion of proteins by pepsin 471 



