32 



THE ROYAL SOCIETY OF CANADA 



Experiment IV. 

 Table lYa. 



Sod Seven Years Old. 



Table IVb. 



Table IVc. 

 Moisture Percentage. 



In Experiment IV, we have an opportunity to compare the influ- 

 ence of the frost on the soil of one single plot, but for varying length 

 of time and different intensity. Influenced by the cleared space 

 around S. (see soil map) the frost penetrated in a horizontal direction 

 in the soil of the snow covered lawn, so that the soil at A. was more 

 frozen and for a greater length of time than the soil at B. or C. In 

 each case the soil was not frozen for a sufficient length of time to allow 

 for a bacterial increase as observed during March in experiments 

 mentioned before. On the 15th of February the snow was removed 

 round C and during the night the plot was exposed to a temperature 

 of -10° F. causing the frost to penetrate 8". 



The severe frost in the exposed plot S. had caused a decrease in 

 the bacteria present as a comparison with the other analyses shows. 

 Further, the sudden penetration of frost in plot II had reduced the 



