Fungous Flora of the Soil 433 



Cohn's nutrient solution. — Prepared according to formula given by 

 Smith (05). 



Distilled water i ,000. 



Acid potassium phosphate (KH2PO4) 5 . 



Magnesium sulfate 5 , 



Neutral ammonium tartrate 10 . 



Potassium chlorid 



Lactic acid solution. — Prepared according to the following formula: 



Water i , 000 . 



Lactic acid 9 . 



Lactose solution. — Prepared according to the following formula: 



Water i , 000 . 



Lactose 30. 



All the above liquid media were sterilized in the autoclave for fifteen 

 minutes at 17 to 18 pounds pressure. 



Potato plugs. — These were cut and prepared as usually recommended 

 in bacteriological work. 



Wheat stem plugs. — Stems of mature wheat were cut into pieces approxi- 

 mately three inches long, and three to five were placed in each test tube. 

 Distilled water was now added to cover the lower third of the plugs, and 

 the whole was sterilized in the autoclave for fifteen minutes at 17 to 18 

 pounds pressure. 



Methods of isolation 



Isolations were made from samples A, B, D, and E after the following 

 manner: Plates were poured and the media allowed to cool. While 

 the media were cooling, the tube containing the soil sample was washed 

 externally with mercuric chlorid solution (1-1,000). The cap was taken 

 off, and with a sterile scalpel (sterilized in a gas flame) the soil was removed 

 from the tube to a depth of about one fourth inch. This precludes all 

 possibility of using contaminated soil for inoculation of the plates. The 

 smallest masses of soil that could be taken on the point of a sterile scalpel 

 were taken from the tube and planted in the petri dishes containing the 

 agar. Five such masses were placed at different parts of each dish. 

 Before each planting was made, the scalpel was again flamed. In making 

 the inoculation, the covers of the dishes were raised only sufficiently to 

 allow the introduction of the scalpel and immediately thereafter they 

 were replaced in position. Before inoculating a second dish, the soil was 



('05) Smith, E. F. Bacteria in Relation to Plant Diseases. Carnegie Inst. 

 Washington Pub. 27: 197. 1905. 



