Transactions of The Royal Society of Canada 



SECTION IV 



Series III JUNE AND SEPTEMBER, 1918 



Vol. XII 



Bacteria of Frozen Soils in Quebec. II. 

 By J. Vanderleck, Ch.E. 

 Presented by F. C. Harrison, D.Sc, F.R.S.C. 



(Read May Meeting, 1918.) 



Introduction. 



At the last meeting of the Society (May, 1917), a paper^ was 

 read dealing with the presence of bacteria in Quebec soils during the 

 winter of 1916-17. The final conclusions and summary arrived at 

 were as follows: — 



1. Bacteria increased rapidly in January in all soils where raw 

 material was available for bacterial decomposition. This 

 increase took place in frozen and unfrozen soils. 



2. When raw material was absent this increase did not materialise. 



3. During March in frozen soils a moderate increase in the 

 numbers of bacteria was observed. This increase reached only 

 from twice to four times the original numbers. 



4. Severe frost would check any bacterial development in frozen 

 soil. 



5. A high water content of the soil would counteract the frost 

 action; a low water content would assist in depressing bac- 

 terial development. . 



6. A sudden severe frost killed most of the bacteria in the exposed 

 soil. 



7. As soon as the soil thawed a decrease in numbers of bacteria 

 was observed. 



8. An increase in soil moisture was usually followed by an in- 

 crease in bacteria. 



'Transactions Royal Society of Canada, Ser. Ill, Vol. XI, Section IV, page 

 15. June and September, 1917. 



Sec. IV, Sig. 1 



