240 



Prof. W. B. Bottomley. 



The more rapid growth of the organism in Series II and III was rendered 

 apparent by the fact that a scum was visible on the surface of the liquid in 

 each flask of these series after 24 hours, while the pellicle formed in 

 Series I only after the lapse of 72 hours. 



The results obtained indicated clearly that there is present in the 

 bacterised peat a substance which stimulates plant growth, and that this 

 substance is of a fairly stable nature is shown by the fact that almost as 

 good results were obtained with the extract which had been boiled for five 

 minutes as with the unboiled extract. 



In order to test whether the active substance is present as such in the 

 original peat, or whether it is produced in the bacterised peat as a result of 

 treatment, an extract of the raw peat was made in precisely the same 

 manner and in the same concentration as described for the bacterised peat. 

 Two series of cultures were prepared, the one containing complete food 

 substances in distilled water, the other complete food in alcoholic extract of 

 raw peat. The controls were analysed at once, while the cultures were 

 incubated for eight days at 26° C. as before. No increased growth was 

 apparent in the cultures containing alcoholic extract of raw peat, while the 

 results of analysis, as given below, indicate the absence of any stimulating 

 substance : — 



Table II. 



Series. 



Nitrogen content. 



Nitrogen 

 fixation. 



Mean nitrogen 

 fixation. 









mgrm. 





mgrm. 



mgrm. 





1. 



Control 



0-31 



Mean, 







2. 





0-4 J 



"4 mgrm. 









3. 



Culture 



3-8 





3-4 







4. 





3-9 





3-5 







5. 





3-8 





3 4 



3 5 





6. 





4-0 





3-6 





II. Complete food + alcoholic 



1. 



Control 



2-41 



Mean, 







extract of raw peat 



2. 





2-8J 



2 '6 mgrm. 







3. 



Culture 



4-0 





1-4 







4. 





4-6 





2-0 







5. 





4-6 





2-0 



1 9 





6. 





4-8 





2 -2 





The active substance is evidently produced in the bacterised peat as a result 

 of treatment, and since this treatment consists essentially in the production 

 of soluble humates by bacterial action, a test was made to ascertain whether 

 the chemical production of soluble humates would be equally effective. Two 

 equal portions of raw peat were saturated with solutions containing 1 per cent, 

 of their weight of sodium carbonate, and were stirred at frequent intervals for 



