BY R. GREIG-SMITH. 641 



These considerations lead one to expect tliat the addition of 

 glucose to soil will bring about a more rapid production of bac- 

 teriotoxin. The quantity must not be too great or there will 

 not be a complete fermentation, and any left undecomposed in 

 the soil will, upon extraction with water, act as a nutrient 

 masking the toxic effect. 



A preliminary experiment was made with an alluvial soil 

 which had been in store for some time. It was subsequently 

 considered that a raw soil would have been more suitable as 

 probably containing a more diverse flora, but, unfavourable as 

 the conditions were, the experiment showed that dextrose un- 

 doubtedly assisted the formation of bacteriotoxins. It was 

 somewhat difficult to decide upon the amount of dextrose to add 

 to the soil. Lipman obtained his toxic effects with 10, 20, and 

 30 grams of dextrose to 20 pounds of soil, a quantity roughly 

 equivalent to 0-1%, 0*2%, and 0-3%. He got a pronounced 

 diminution of crop with 0-2% Maze obtained 57 milligrams of 

 glucose from a maize-plant growing in three litres of water. 

 This is approximately equal to 0-02%. These quantities were 

 given and obtained during a growing period, but, to obtain 

 evidence of toxicity in a short time, a smaller amount would 

 probably be better to ensure a complete fermentation. 



The experimental soil was accordingly treated with 0-005% of 

 dextrose, and check-tests without sugar were made at the same 

 time. Two of the conditions for toxin-formation had already 

 been determined. These are, that the soil should contain an 

 amount of moisture equal to about one-quarter of the water- 

 holding capacity, and that the temperature of incubation should 

 be from 22° to 28°. As the laboratory temperature was about 

 25°, the bottles of soil were allowed to stand upon a laV)oratory- 



The tests with no sugar behaved just like previous tests. The 

 nutritive effect was reduced upon incubation, and, although this 



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