THe INFLUENCE OF Low TEMPERATURE ON Sort BAcTERIA 1065 
The results obtained when glycerin was used in varying amounts are 
shown in table 8. A remarkable protective action was exerted by the 
glycerin when the concentration was 1 per cent and above. With 
decreasing amounts of glycerin down to 0.01 per cent, there was a rapid 
increase in the percentage of bacteria killed. When the concentration of 
glycerin was raised to 5 and 10 per cent, there was an actual increase in the 
number of bacteria, as is shown by the colonies on the agar plates. This 
seeming increase was perhaps due to the breaking up of the clumps of 
bacteria. It is possible that in the nutrient solution containing 1 per 
cent of glycerin a great many of the organisms were killed, and that the 
high counts were due to the breaking up of the masses of bacteria. There 
was little or no growth in the nutrient solutions containing 15 per cent of 
glycerin. 
INFLUENCE OF DEXTROSE 
The results from the higher concentrations of media using glycerin 
and dextrose verified the finding of Maximow in his work with red cabbage 
and Tradescantia discolor. So long as the temperature of the frozen 
medium was maintained above the eutectic point of the substance used, 
the protective action was noted. If the above findings hold true in 
regard to the bacterial cell, the concentration of the medium should have 
no effect when the temperature is lowered to a point at which the glycerin 
and the dextrose will crystallize out. To test this latter point, the bacteria 
in the solutions described above were subjected to a temperature of 
-190° C., using ice and salt. 
The results obtained with the different concentrations of media when 
exposed to a temperature of —190° C. using liquid air, and to a temperature 
of —15° C. using ice and salt, are given in table 9. There was the same 
marked protective action due to the increased concentration of the medium 
when the solutions were frozen in ice and salt for two hours, as was shown 
by glycerin (table 8). When the bacteria were subjected to the 
temperature of liquid air for five minutes the concentration of the medium 
had little or no effect. These results would seem to substantiate the 
foregoing theory, that when the temperature is lowered below that of the 
eutectic point of the sugars added, the concentration of the medium has 
no effect. 
In table 9 the percentage of bacteria killed is based on the number of 
colonies growing on the plates poured before and after treatment of the 
