158 CONTItlBUTIONS TO OUR KNOWLEDGE OF SOIL-FERTILJTY, xvi., 



Portions of the air-dried mould containing 14 grams of dry 

 matter were put into Petri-dishes and sterilised. They were 

 infected with cultures of Bac. T.P.2, and of Actinomyces 10, and 

 the moisture raised to 40%. The extracts were prepared by 

 shaking each portion with 500 c.c of distilled water. 



The growth of the accidentally introduced Penicillium resulted 

 in a flattening of the dilution-curves, and in a diminution of the 

 acidity. From this, it must be inferred that the acidity was 

 chiefly responsible for the toxicity of the extracts. To test the 

 matter, a further experiment was made with partially neutralised 

 mould, and with neutralised extracts. 



Four-punce glass bottles were used instead of Petri-dishes, and, 

 into each, 18-2 grams of mould, containing 14 grams of dry 

 matter, were introduced. They were sterilised at 130° for two 

 hours, moistened with 3 c.c. of sterile water, and steamed for an 

 hour. The steaming proved to be unnecessary, as portions of 

 the heated soil proved to be sterile. One of the portions was 

 infected with a Fusarium, another with a Rhizobium, a third 

 served as a control, a fourth was treated with enough lime-water 

 to neutralise the apparent acidity, and the last was subjected to 

 the vapour of ammonia for a couple of hours. The moisture in 

 them all was brought to 40%. The extract of the raw mould 

 was found to be very acid, 1000 c.c. containing the equivalent of 



