Tue INFLUENCE OF Low TEMPERATURE ON Sort BAcTERIA 1067 
It is interesting to note that Conn’s counts for the frozen soil were 
higher than those for the unfrozen soil, whereas the counts of Brown and 
Smith for the frozen soil were in all cases except one far below those for 
the unfrozen soil, and in the sample taken on March 1, in which the count 
was above normal, the moisture content had been increased from 15.76 
to 26.57 per cent. Regardless of the fact that three samples out of the 
four taken showed a lower bacteria count than the normal soil, Brown 
and Smith concluded that their results substantiated the conclusion of 
Conn that bacteria do reproduce in increasing numbers in frozen soil. 
It is interesting to note the very close correlation that can be drawn 
between the increase in the number of bacteria in frozen soils and the 
increase in the individual over the group counts, as shown by Conn in 
recent publications (1917 and 1918). In both cases the increase was 
between 25 and 50 per cent, the individual count showing the greater gains. 
The gains obtained by the author with the frozen samples are in very close 
keeping with the preceding. 
The moisture content and the rate of thaw are the important factors 
that determine to a large extent the breaking-up process. This point is 
well brought out in the work of Harder. When the frozen soil was thawed 
rapidly by rain there were a large number of organisms occurring in 
the thawed soil, but when the thaw was gradual the number dropped back 
to about normal. The only high count obtained by Brown and Smith 
can be explained in somewhat, the same manner. Their sample taken on 
February 11 showed a moisture content: of 15.7 per cent and a bacteria 
count of 4,744,000 colonies; whereas their sample taken on March 1 
showed a moisture content of 26.5 per cent and a bacteria count of 
16,870,000. Between these two dates the moisture content rose 68 per 
cent, which would indicate that there had been a thaw followed by a 
freeze, resulting in a breaking up of the masses of bacteria. 
That frozen soil is not as favorable a medium as unfrozen soil for the 
growth of bacteria is shown by the results obtamed by Harder when 
soils were treated with dextrose. His results show a retardation in 
growth caused by low temperature, which even a much higher moisture 
content was not sufficient to counteract. They substantiate the theory 
that the increased count in frozen soils is due to a breaking up of the 
clumps of bacteria, for such an increase should be more marked in soils 
having a high moisture content and this condition was found to be true 
