BY R. GREiG-SMITtt. 



16; 



be a difference of 3 c.c. The total differences would, therefore, 

 amount to 60 5 c.c. of N/100 acid for the total acidity developed 

 during sterilisation and removable by washittg ivitk icater. In 

 terms of the organic matter of the mould, this means that 100 

 grams during sterilisation developed an acidity equal to 605 c c. 

 of normal acid, equivalent to 0-36% grams of acetic acid. 



A portion of the sterilised leaf-mould, containing 10 grams of 

 organic matter, upon being gradually moistened with water, was 

 found to form a fairly coherent ball when pressed in the hand 

 after the addition of 1 5 c.c. of water to each portion. Accord- 

 ingly, 15 c.c. of water containing 6 c.c. of N/10 sodium bicar- 

 bonate were added to each portion, which was thoroughly mixed 

 and pressed down. Suspensions of the bacteria in 1 c.c. of water 

 were subsequently added, mixed, and pressed. 



After an incubation of five days, extracts were made, and 

 their effect upon the growth of Bac. j^vodigiosus noted. 



Experiment xvii. 



I 



The numbers in the control and in the T.P.2 tests are virtu- 

 ally the same, and evidently no growth of the bacillus had 

 occurred. The numbers with Rhizobium are different, not only 

 in the acid extract, but also after it had been neutralised with 

 soda. The fact that Rhizobium can grow in the partially acid 

 leaf-mould is a point worth noting. It is needless to discuss the 

 possible formation of toxins with these leaf-moulds, and the re- 



