34 



THE ROYAL SOCIETY OF CANADA 



numbers of bacteria by about two-thirds, although the moisture 

 had increased. Here we have an example where a movement of soil 

 moisture to a soil layer is accompanied by a decrease in bacteria. 



Conclusions. 



1. Severe frost checked bacterial development, especially where 

 the water percentage of the soil was low. 



2. A sudden penetration of frost killed many bacteria. 



3. A movement in soil moisture to a higher percentage was 



apparently not accompanied by a movement in bacteria to any 



noticeable degree. 



Table V. 



Cultivated Plot, not plowed, on Top of Hill. 



Table Va. 



Feb. 5.. 

 Apl. 16. 



Table Vb. 



Moisture Percentage. 



Feb. 5.. 

 Apl. 16. 



26" I 31-6 

 3"-16"l 29-5 



32 

 22-7 



128 

 18-8 



17-2 

 12-7 



12-8 



14-8 



Experiment V. 



This experiment was conducted at the top of a hill, and the 

 field was the one mentioned in Experiment I. A crop of garden 

 peas had been grown on it during the season, and in November this 

 section was plowed. The roots of the pea vines supplied, however, 

 ample raw materi;,] for decomposition. The field was sampled for 

 the first time on February 5th. At this early date the frost had 

 penetrated 26 inches and large numbers of bacteria were counted 

 on the 3 upper levels (4", 8" and 12" below the surface). In the 

 following weeks the depth of frost was tested several times, but no 

 bacterial examination made until April 16th. The four depths of 

 sampling (4", 8", 12" and 16") were still frozen, the upper 3" having 



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