PLATE I 

 Plate cultures of soil organisms growing on agar: 



Fig. I. — Colonies of organisms from untreated soil. 



Fig. 2. — Colonies from soil treated with 2 per cent of carbon bisulphid. 



Fig. 3. — Colonies from soil treated with 2 per cent of carbon bisulphid and evapo- 

 rated. 



Fig. 4. — Colonies from soil treated with 2 per cent of carbon bisulphid, evaporated, 

 and reinoctilated with 5 per cent of soil from an untreated jar. 



(20) 



