4 THE ROYAL SOCIETY OF CANADA 



Association. The soil extract gelatine was prepared according to 

 directions given by H. J. Conn. The plates were incubated for 

 seven days at a temperature of 14°C. before being counted. 



Weather. 



The weather conditions throughout the course of the experiment 

 have been tabulated and snow and rainfall recorded on the tempera- 

 ture chart. The chart gives the daily mean average for the winter 

 of 1917-18. During this winter the temperature dropped below 

 freezing point in the middle of November and remained very low 

 until March 1st. Four times in this period the mercury went above 

 freezing point although only for a few hours each time, but these short 

 periods of thaw were accompanied by heavy rainfalls. One inch of 

 rain fell during each thaw in December, but the absence of snow 

 allowed this precipitation to be carried off very easily over the frozen 

 ground. The thaws in February were accompanied by a rainfall of 

 more than two inches. The heavy snow blanket kept this moisture 

 in special places, and one experimental plot in Experiment II was 

 covered with a layer of water nearly two feet deep. The heavy snow 

 prevented this water from freezing. The very mild weather in the 

 second half»of March and the total absence of any precipitation 

 allowed the snow to disappear rapidly and heavy rain showers in the 

 beginning of April assisted in the thawing of the frozen soil. Thus 

 in spite of the very deep frost penetration the soil was thawed earlier 

 than in former milder winters. 



The snowfall until February was rather light, but in addition to 

 this it fell on hard-frozen, icy ground and the prevailing high winds 

 swept it from the fields in protected corners. Thus in the middle of 

 January the snow covering of the different fields and plots was only 

 two, one, two and five inches respectively, although the total snowfall 

 for the same date was twenty-six inches. On this bare ground four 

 severe cold spells were experienced in December only. In three the 

 daily mean temperature was — 10°F., but in the Christmas cold wave 

 the daily mean for three consecutive days was — 24°F. Under such 

 circumstances it cannot be surprising that the frost penetrated more 

 than three feet. 



The data obtained are again arranged in five sets of three tables 

 each, and one diagram. Table A. gives the total bacterial content 

 per gram of dry soil; Table C. the moisture percentage at depth of 

 sampling, and Table B. compares the number of bacteria appearing 

 on beef peptone media with those on soil extract gelatine. 



