BY R. GRBIG-SMITH. 699 



The last few experiments shoAv tliat treatment with fat- 

 solvents brings about an alteration in the soil, whereby the 

 upper layers are less nutritive than the lower, and give up a 

 smaller amount of toxin to an excess of water. The nutritive 

 substances and toxins of the upper layers are less accessible 

 to bacteria, and less easv of extraction than the lower. This 

 is a strong indication that the agricere has been translated 

 upwards by the fat-solvent, and, although deposited in a 

 manner quite diffrent from its original condition, is still 

 able to exhibit, though to a less degree, its power of protect- 

 ing the soil-particles from attack. 



Summa?-}/. 



Rain washes the soil-toxins into the subsoil. 



The volatile disinfectants or fat-solvents have no action 

 upon the soil-toxins. 



Traces of volatile disinfectants have no action upon the 

 bacterid under experimental conditions. 



Substances capable of acting as antitoxins are at present 

 unknown. 



The action of heat upon soil is, first, to destroy the original 

 toxin, and then to produce heat toxins, the one action 

 running into the other 



After treatment with volatile disinfectants, the toxins or 

 heated soils arc more easily dissolved by water than the toxins 

 of untreated soils. 



Treatment with volatile disinfectants induces an increased 

 growth of bacteria in soils in which the protozoa, etc , have 

 been destroyed by moist or dry heat at 65°-75°. 



The upper layers of soils which have been treated by vola- 

 tile disinfectants are less nutritive to bacteria than the lower. 

 Conversely, more toxin is given up to water. 



These results point to one of the chief actions of the vola- 

 tile disinfectants being to translate the agricere of the soil, 

 and enable the nutrients to be made more available ; that is, 

 they act as fat-solvents. 



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