1044 A. F. Vass 
Regarding the resistance of bacteria to low temperatures, it was found by 
Schumacher (1874)!, Géppert (1875), Frisch (cited by Pfeffer, 1903:238), 
~ Dewar and McHendrick (cited by Pfeffer, 1903:238), and Meyer (1900), 
that neither the spores nor the vegetative cells were killed by an exposure 
of several hours to temperatures ranging from —20° to —200° C. 
Pictet and Yung (1884) exposed Micrococcus lutea and the vegetative 
cells of Bacillus anthracis to a temperature of —70° C. for one hundred 
and eight hours; this resulted in the death of the bacteria, as did also a 
temperature of —130° C. for twenty hours. The spores of Bacillus 
subtilis, Bacillus anthracis, and Bacillus ulna were not affected by the 
above-named temperatures. These results verified the conclusion of 
Melsens (1870), that long exposure of the yeast cells to —91° C. greatly 
decreases the fermentative activity. The enzyme of the yeast and the 
toxins of the poisonous bacteria were destroyed by exposure to extremely 
low temperatures. In his later work with microbes and diatoms, Pictet 
(1893) found that continued cold at —200° C. did not destroy these. 
In studying the bacterial flora of snow, Janowski (1888) noted that 
continued low temperatures had very little effect on the bacteria. He 
found several hundred bacteria per cubic centimeter in water from snow. 
Forster (1892) noted that the kinds of bacteria able to grow at 0° C. 
were not very numerous, but they seemed to be widely distributed, 
especially in water and on the surface and in the intestinal tract of both 
fresh- and salt-water fish. 
In his work with Bacillus anthracis, Klepzoff (1895) noted that long 
exposure to low temperatures reduced the virulence of the organism and 
that the bacteria in blood and various organs were killed by exposing 
them to a temperature of —24° C. for twelve days. The colonies on 
agar plates were destroyed by exposing them for twenty-five days to the 
above-named temperature. 
Kasansky (1899) exposed the pest bacillus and the diphtheria bacillus 
to temperatures ranging from — 10° to —30° C. for five months and found 
that they were alive at the end of the experiment. 
In their investigations with pure cultures of Bacillus typhosus, Sedg- 
wick and Winslow (1900) found that from 30 to 60 per cent of the bacteria 
were destroyed during the first hour of freezing, and at the end of two 
weeks 99 per cent were destroyed. They studied the effect of alternate 
ar Dates in parenthesis refer to Literature cited, pages 1071 to 1074. 
