686 CONTRIBUTIONS TO OUK KNOWLEDGE OF SOIL-FERTILITY, iv., 



terial growth. Potassium permanganate was not toxic, but 

 the soil-particles had apparently become covered with the 

 reduced salt, as it became very absorbent ; there was no dif- 

 ference between the treated and the untreated portions. 



The Actio7i of Chloroform- Water upon the Growth of 

 Bacteria in Soil. — As a rule, substances that are toxic in com- 

 paratively large doses, are generally stimulative in compara- 

 tively small quantities, and it is just possible that traces of 

 the volatile disinfectant adhere to the soil-particles, and 

 stimulate the growth of bacteria. It had been shown, in a 

 preliminary experiment, that small quantities of chloroform 

 did not prohibit the growth of bacteria, and an experiment 

 was made to see if there could be any stimulation. Several 

 20 gr. portions of soil were put into bottles, and mixtures of 

 chloroform-water and sterile tap-water in varying proportions 

 were added, along with a suspension of Bac. prodigiosus. The 

 total quantity of fluid added was 12 c.c. to each bottle. The 

 tests were incubated overnight at 30°, and, on the following 

 day, dilutions were made, and the number of bacteria deter- 

 mined. 



Experiment vi. 



So far as Bac. prodir/iosus is concerned, it is seen that 

 chloroform-water restrains the growth, but that a multipli- 

 cation occurs in the presence of one part of chloroform-water 



* The increased growth of Bac. prodigiosus had checked these bacteria. 



