BY R. GREIG-SMITH. 817 



The result with potassium sulphate is interesting, as Baker has 

 shown that, in the grains of cereals, there exists a toxin which is 

 toxic to brewery -yeasts. This toxin is also thermolabile. It is, 

 however, destroyed by potassium sulphate, and thus differs from 

 the soil-toxin. Whitney had an hypothesis that manures, when 

 applied to soil, simply destroy the toxins that have exuded from 

 plants, and enable the fertilising matters naturally in the soil to 

 assist the growth of crops. Potassium sulphate is such a manure, 

 and, as far as we know, does not destroy the toxiu. 



The experiments wliich have been quoted, show that a bacterio- 

 toxin is unquestionably present in soils. The various sidelights 

 that have been thrown upon its nature, show that it is present in 

 soils in quantity which varies with the soil, a richer soil probably 

 containiijg less, a poorer soil more. It is slowly destroyed by 

 storage in aqueous solution, and rapidly broken up by heat. It 

 is more soluble in solutions of salts than in water, and indifferent 

 saline solutions it has a different solubility. It does not appear 

 to be of the same nature as the thermolabile toxin occurring in 

 the grains of cereals. 



Thk Presence of Agricere in Soils. 



In treating garden-soil with an excess of carbon bisulphide, it 

 was observed that, upon the surface, a curious moss-like efflores- 

 cence appeared as the disinfectant evaporated. The colour was 

 at first yellow, then it became greenish, then grey, and finally the 

 efflorescence disappeared. Microscopically it consisted of branch- 

 ing processes recalling coral. When picked up with the blade of 

 a knife, it melted to a brown wax-like substance. Subsequently 

 a similar phenomenon was noted when chloroform had been 

 employed. 



Following up this observation, it was found that the disin- 

 fectants dissolve a wax, or group of wax-like bodies, which are 

 present in the soil. The solvents appear to differ in their powers 

 of extraction, not only in the appearance, but also in the quantity 

 of the extract; thus petroleum- ether took out of garden-soil a. 

 brownish-yellow wax, alcohol a brown wax, and chloroform ii. 

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