696 CONTRIBUTIONS TO OUR KNOWLEDGK OF SOIL-FKRTILITY, iv., 



kill off phagocytic protozoa. If the treatment with antisep- 

 tics facilitates the diffusion of toxins, surely it will also assist 

 the more rapid diffusion of the nutritive matter. 



When the disinfectant is added to the soil in quantity suf- 

 ficient to soak it thoroughly, it is noticed that, as the fat- 

 solvent evaporates, the agricere is partly deposited as a ring 

 upon the containing vessel at the surface of the soil. It is not 

 expected that all the agricere is in the extreme upper layers, 

 any more than that one extraction with solvent would be 

 enough to remove all the fatty matter. As a matter of fact, 

 the soil has to be percolated for some time with solvent in 

 order to remove all the agricere. Upon moistening the soil 

 with chloroform or ether, and allowing the disinfectant to 

 evaporate, the agricere should be chiefly in the upper layers, 

 and the lower strata should be comparatively free from it. 

 Experiment showed that such is the case. 



A hundred grams of air-dried soil (No. 1) were placed in a 

 beaker, and soaked with ether (Merck). When the odour had 

 passed off, the layers were carefully abstracted, and weighed 

 (20gr.) portions were moistened with 2 c.c. of a suspension of 

 Bac. prodigiostis, and incubated overnight. Next day, the 

 soils were shaken up with water, and dilutions prepared for 

 the bacterial count. 



Experiment xx. 



The comparative poverty of the lower layers of the soil in 

 agricere, is shown by the greater increase in the growth of 

 the bacteria. 



In another experiment, 500 gr. of a garden-soil were placed 

 in a beaker, and wetted with ether, and the solvent was 



