380 PHYSIOLOGY OF BACTERIA 



Cohen also computed the temperature coefficients of 

 starvation. These coefficients are too low because at 

 lower temperatures, the cold-shock is superposed, which 

 increased the death rate. It is interesting to note that 

 Hinds as well as Cohen found that Bad. typhosum had 

 a lower temperature coefficient than Bad. coli. (1.71 

 against 4.30 between 20°C. and 37°C.) 



(6) STARVATION IN SALT SOLUTIONS 



While the above data relate to bacteria with practically 

 no food whatever, other data are available where at 

 least the minerals were supplied. 



Zeug (1920) found that standard physiological salt solu- 

 tion caused some bacteria to die faster than they did 

 with distilled water. He then tried salt solutions which 

 would be less toxic to bacteria, and found that solutions 

 of one salt were quite unsatisfactory, but mixtures of 

 several salts were capable of keeping bacteria alive for a 

 few days without much loss of viability. Most sensitive 

 against 0.85% NaCl were Micrococcus pyogenes, Bad. 

 vulgare, Vibrio Metchnikovi, while Bad. acidi ladici, 

 Bad. septicemiae hemorrhagicae and Ps. pyocyanea 

 decreased but little in three days and Bad. typhi murium 

 even increased. Zeug then set out to find suitable 

 solutions for the three sensitive organisms. 



The result of this study was that different species 

 required different salt mixtures for long viability. The 

 solution best fitted for one was not satisfactory for the 

 other. This is shown in Table 123, where the optimum 

 mixture for Micr. pyogenes is seen to cause a fairly rapid 

 death of Bad. vulgare, while the solution best suited 

 for Bad. vulgare is not very satisfactory for Micr. 

 pyogenes. Some of the best combinations are shown in 

 Table 124. 



