CHAPTER IV. 



QUANTITATIVE ANALYSIS continued. 



THE BACTERIAL CONTENTS OF THE VARIOUS 

 SOURCES OF SUPPLY. 



Snow. Janowski examined snow which had been lying on the 

 ground for some time ; the superficial layers were removed in 

 order to avoid organisms which might have been derived from 

 the air. The sample was then taken, placed in a test-tube and 

 melted. One c.c. of snow-water being used for each plate the 

 following results were obtained : 



24 hours old. 48 hours old. 72 hours old. 96 hours old. 



Sample. Air temperature Air temperature Air temperature Air temperature 



6 C. 6'5"C. 10 C. 11 '6 C. 



I. 2 18 228 145 



II. 4 20 212 



Schmelck found in the melted water from snow on an iceberg 

 in Norway 2 bacteria and 2 moulds per c.c. Janowski also 

 examined freshly-fallen snow, and from one c.c. of the melted 

 snow-water obtained the number of micro-organisms given in the 

 following table : 



Taken ou Feb. Taken 011 Feb. Taken on Feb. Taken on Feb. 



2, 1888. 20, 1888. 28, 1888. 29, 1888. 



Air temperature Air temperature Air temperature Air temperature 



7-20 C. 11 C. 12 C. 3-4 C. 



I. 34 203 140 134 



II. 38 384 168 463 



Thus, even at a low temperature, snow has been found to 

 contain micro-organisms, and the number appears to increase 

 with the length of time the snow has been lying on the ground. 



Ice. Heyroth examined ice obtained from various places in 

 Berlin. Blocks of ice were broken and portions removed from 

 the centre, were then melted in sterile test-tubes and the ice- 



