1056 A. F. Vass 
per cent above that of the count made using water at 1°C. When the soil 
was allowed to thaw in the air the difference was less marked. It is 
interesting to note that when the temperature of the water used in plating 
the soil was raised to 40° C. there was always a drop in the counts. This 
may have been due to the death of the bacteria caused by the sudden 
change to higher or lower temperature. It seems more probable, however, 
that the higher temperatures may cause a greater or less coagulation of 
the masses, resulting in fewer colonies on the plates. 
TABLE 1. Errect or Rate oF THAW ON THE BactTEeRIA Count IN Fiexp Soits 
Bacteria 
Sample Treatment per gram of 
dry soil 
1 ea tars teat A eae Wrater/added! at) il oiC i iytsioe ae oe eee 3,100,000 
Dear reloak Seen tye weed Wiater-added atol0% ©. tery. oe a ssh) a eee 5,200 ,000 
Ca PE as Panett eae nae lly Water added at 205 Cuniit. 2) cust a ene 6,000 ,000 
ANN SSO aU CR Rae Re ete Watervadded at 303:C \. 5 45). 3. a ee a 9,300,000 
Epa ase 9 a eR Water added atj402 Cy ah vanny. ee eee 6,700,000 
Gli keke sekae re may) Soilithawedinyainjat: lS Cleese ee 5,000 ,000 
iz A SONAR Sar Soilithawedintainatl0 Cees 35 e eeee ee 6, 100 ,000 
tery raN Eten sper) ON I Soil thawed in airat 202 Cis a ee ane 6,300,000 
SAEs ab Me ry Dah cars Soil thawed in air at 30° C......... Mee Ae 5 6,900 ,000 
LOR Se ees ete Soilithawed)in\airsat AO aC re ee 5,800,000 
SOILS FROZEN IN THE LABORATORY 
Samples of soil that had been kept in a moist condition in the laboratory 
were used to test the effect of short periods of freezing and different rates 
of thaw. Counts were made of the normal soil containing 30 per cent of 
moisture, and the samples were then exposed to a temperature of —15° C. 
for twenty-four hours. In table 2 is shown the effect of short Dee of 
freezing and different rates of thaw: 
TABLE 2. Errect or Rate or THAW ON THE BactTERIA Count IN LABORATORY SOILS 
Bacteria 
Sample Treatment per gram of 
dry soil 
I Gehaiceativesianty Aiceciay ek tle Normal eos a ar oe Gee etna ote ae) aes cc 4,600,000 
Dire nell a HORP a a te Frozen 2 hours at —-16° C., thawed in room.........} 6,600,000 
SEAR TERERE ENP U ER Sh ca Frozen 2 hours at —16° C., water added at. 30°.C....] 9,800,000 
