822b contributions to our knowledge of soiL-FERTrLrrr, 



The result shows that the toxin is toxic towards the bacteria 

 naturally occurring in the same soils from which the extract was 

 obtained. Although the toxic action is not so pronounced as 

 with Bac. prodigiosus, yet it is active, and is destroyed by heat. 

 The chief organism that grew in the extracts was a uiiciobe 

 identi6ed as Bac. higetninus major. It is remarkably inert; it 

 does not liquefy gelatine, does not produce indol, or reduce- 

 nitrate, and does not ferment dextrose. 



Summary. 



Water extracts from soil a substance which is filterable through 

 porcelain, and which is toxic to bacteria. 



The toxicity is made evident by the retardation of growth, or 

 by the destruction of the bacteria. 



The toxin is destroyed by heat, by sunlight, and by storage. 

 It slowly disappears from air-dried soil, and rapidly decays in^ 

 aqueous solution. 



It is not destroyed by salts, such as sodium chloride, potassium,, 

 or magnesium sulphate. 



Soils vary in the amount of toxin they contain; good soils 

 containing less, poor .soils more. 



The particles of soil are covered or " waterproofed " with soil- 

 wax or " agricere," which consists of a mixture of saponifiable 

 and unsaponifiable bodies. 



The wax-solvents (volatile disinfectants) alter the distribution, 

 of the agricere by carrying it to the surface of the soil, and 

 causing it to be segregated on the points of the soil-particle.s. 



With the removal of the " waterproofing," the soil-nutrients 

 are more easily dissolved by «oil-water, and attacked by bacteria.. 



