BY R. OUEIG-SMITH. 



695 



KXPERIMKNT xix. 



The general result of these experiments with pasteurised 

 soil, is to show that, in the absence of any possible action of 

 protozoa, etc., the solvent has a decided and considerable 

 action of its own in enabling the bacteria to grow. As the 

 solvent has no action upon the toxin, this can only be brought 

 about by the nutrients being made more available, and is a 

 very strong argument in favour of the idea that the segrega- 

 tion of the agricere is the chief action of the solvents or vola- 

 tile disinfectants. 



T/ic Distribution of the Agricere in the Soil, after Treat- 

 ment with Solvents. — It has already been shown (Experiments 

 iii. and iv.) that soils which have been treated with an anti- 

 septic, yield extracts which are more toxic than those obtained 

 from untreated soils, and that soils give up their heat-toxins 

 more freely after treatment (Experiments xi., xii., xiii.). So 

 far as the extracts are concerned, the quantity of extracting 

 material which has generally been used, viz., '200 c.c. for 200 

 gr., has ensured a greater diffusion of the toxins than of the 

 nutrients from the soil-particles. In the experiments with 

 heated soils, doubtless the quantity of toxin produced has 

 been so great as to overwhelm the action of the nutrients. 

 Still the fact, that a greater quantity of toxin does diffuse 

 out, shows that the fat-solvent has done somethine more than 



61 



