1064 A. F. Vass 
INFLUENCE OF GLYCERIN 
If the protective action is due to the greater concentration of the 
solution, the addition of sugar or similar substances should have the same 
effect. In order to test the influence of the concentration of the medium, 
a very weak nutrient solution was prepared as follows: Dibasic potassium 
phosphate 0.05 gram, magnesium sulfate 0.05 gram, sodium chloride 0.05 
gram, calcium sulfate 0.05 gram, distilled water 1000 cubic centimeters. 
Glycerin was added at the following rates: 0.01, 0.05, 0.1, 0.5, 1, 5, 10, and 
15 per cent. 
Test tubes containing 10 cubic centimeters of the above nutrient solution 
with glycerin added in increasing amounts, were inoculated with a culture 
of Bacillus radicicola and incubated for five days at 25° C. At the end of 
that period, counts were made of the number of bacteria per cubic centi- 
meter in each tube, by means of the agar plates. The tubes were then 
frozen for thirty minutes in ice and salt at a temperature of -15° C. At the 
end of the half hour the tubes were thawed by placing them in water at 
15° C., and were plated as in the preceding experiments. Care was 
taken to have all conditions uniform, for the earlier findings indicate 
that a difference in the temperature of the water blanks or in the rate of 
thaw might make a difference in these results. All counts were made at 
the end of five days incubation. Nine plates were poured from each tube 
and the experiment was run in triplicate, so that each count represents 
the average of twenty-seven plates. 
TABLE 8. INFLUENCE oF GLYCERIN ON THE DEATH OF BACTERIA WHEN 
Frozen av —15° C. 
Bacteria 
Glycerin Normal count Per cent 
Sample (per cent) bacteria after being | of bacteria 
count frozen for killed 
15 minutes 
1 eee ec aA a inert a elec a Ri a None 5,600 ,000 236 ,000 96 
PA AMES sare te Sten Al ni aN ey AA toa 0.01 12,300 ,000 984,000 92 
SSI eioree acy cnt eee etc smi REE 0.05 13,600,000 | 1,768,000 87 
A EUR eee AD Lk SC Rol ed oe Oral 17,000,000 | 10,600,000 41 
Ooh at tre IE Ga ees teN ORIEL aL OPN ERE 0.5 21,000,000 | 11,550,000 45 
GE ire ere aay ca MMS er ie 1.0 23,000,000 | 23,100,000 0 
Tica Ais pty ALIVE cane ke he Ged ies Ac 5.0 24,300,000 | 28,200,000 0 
(SPRATT aniNUgcor Inala, Guapeaia OH 10.0 920 ,000 546 ,000 0 
Oe ihe Baca Me ue hts aE CURT 15.0 No growth | No growth | ........... 
