Studies on Salt Action. 



131 



This hypothesis explains why the increase in osmotic pressure, 

 viscosity, and the swelling of gelatin caused by the salt does not 

 become noticeable unless the excess of salt is washed away, since 

 the presence of the salt represses the electrolytic dissociation of 

 the gelatin salt formed. 



Some of the data on which these conclusions are based have 

 recently been published. 1 



187 (1365) 



Studies on salt action. II. The effect of transfer from stronger 

 to weaker salt solutions upon the viability of bacteria in water. 



By C.-E. A. WlNSLOW and I. S. Falk. 



[From the Department of Public Health, Yale School of Medicine.] 



In continuation of work previously reported, upon the via- 

 bility of B. communis in salt solutions of various kinds, 2 we have 

 studied the effect of transfer from salt solutions to weaker salt 

 solutions, in order to see if phenomena could be detected analogous 

 to those observed by Loeb 3 and others in the study of the influence 

 of salt solutions upon the swelling of animal membranes and 

 powdered colloids. 



B. communis was grown on nutrient agar slants at 37 0 C. for 

 16-18 hours. The growth was washed off in pure redistilled water, 

 shaken for five minutes to break up clumps and added in 1 c.c. 

 portions to the electrolyte solutions in which the preliminary 

 treatment was to be accomplished ("primary" solutions), which 

 had been previously warmed to 37 0 C. The solutions were then 

 shaken for one minute to give a homogeneous suspension, 1 c.c. 

 was withdrawn and agar plates poured. The bottles containing 

 the suspensions were then replaced in the incubator at 37 0 C. and 

 kept there for 30 minutes (in one case 60 minutes). At the end of 

 this interval plates were again made, 1 c.c. withdrawn and trans- 

 ferred to another bottle containing 99 c.c. of water or salt solution 

 ("secondary" solution). These secondary solution bottles were 



1 Loeb, J., J. Biol. Chem., 1917. XXXI, 343; 1918, XXXIII, 531; XXXIV, 77; 



395- 



2 Proc. Soc. Exp. Biol, and Med., 1918, Vol. XV, p. 67. 



3 Jour. Biol. Chem., Vol. XXX, p. 343. 



