738 CONTRIBUTIONS TO OUR KNOWLEDGE OF SOIL-FERTILITY, vii.-xi., 



not rise from below. The production may take place rapidly, as a 

 sample taken after a rainfall of 4-75 inches, and stored in the 

 laboratory for three days, showed the following: — 

 Experiment i. 



Raw extract, unboiled . 

 Extract boiled £ hour . 

 Extract boiled one hour 

 Saline-control 



100 bacteria at 22° became 



3 



1 

 20 



228 



Again, a soil was extracted at once, and after storage in a bucket, 

 in the laboratory, for seven days, during which, the moisture fell 

 from 10% to 8%. 



Experiment ii. 



A soil, which was nutritive in the fresh condition, was incubated 

 at 28° for 14 days. Unfortunately, the plug in the bottle permit- 

 ted the soil to dry, and the moisture fell from 10% to 4-5%, so 

 that the conditions for toxin-formation and preservation were not 

 the most favourable. However, the soil became toxic, as the follow- 

 ing shows: — 



Experiment iii. 



The increase of toxicity is seen upon comparing the undiluted 

 numbers with the water-controls. It is also seen in all dilutions. 



