INFLUENCE OF TEMPERATURE AND HYDROGEN ION 



CONCENTRATION UPON THE SPORE CYCLE OF 



BACILLUS SUBTILIS. 



By ARAO ITANO and JAMES NEILL 



{From the Department of Microbiology, Experiment Station, Massachusetts 

 Agricultural College, Amherst.) 



(Received for publication, December 31, 1918.) 



The investigation here reported deals with the influence of hydrogen 

 ion concentration at different temperatures upon the spore cycle of 

 Bacillus suhtilis} This microorganism was chosen because it is a 

 classical spore-bearing species, which had been used in our previous 

 investigations on the relation of the hydrogen ion concentration of 

 the medium to proteolytic activity. 



TABLE I. 



Limiting Reactions* 



Organism. 



B. coli 



" " (low gas ratio group) , 



Streptococcus, Group I 



" II 



S. erysipelatis 



B. siibtilis (acid limit) 



" (alkali limit) 



Author. 



Michaelis and Marcora.f 

 Clark, 1915. t 

 Ayers, 1916.§ 



" 1916.§ 

 Itano, 1916.11 



" 1916.11 



" 1916.11 



* Clark, W. M., and Lubs, H. A., J. Bacterial., 1917, ii, 1, 222. 



t Michaelis, L., and Marcora, F., Immunildtsforsch., Orig., 1912, xiv, 170. 



i Clark, W. M., /. Biol. Chem., 1915, xxii, 87. 



§ Ayers, S. H., /. Bacterial., 1916, i, 84. 



II Itano, A., Massachusetts Agric. Exp. Sta., Bull. 167, 1916, 139. 



^ The same strain of this species was used as in the previous investigations on 

 proteolytic activity; the strain was obtained from the American Museum of Nat- 

 ural History. 



421 



