TRANSACTIONS OF SUB-SECTION B. 581 



certain market and prompt payment for his crop. The ' saturation lime ' given 

 gratis to the farmer contains all the chief manorial ingredients and is of distinct 

 manurial value. The dried slices or pulp (the so-called ' Protos ') are said to 

 possess a greater feeding-value than either hay, bran, barley, or the commonly 

 used meals and cakes. 



From an examination of Continental experiences it is considered that a 

 factory dealing with the produce of about 2,500 acres is the most profitable. 

 Such a factory would deal with, say, 36,000 to 50,000 tons of roots during a 

 campaign of not more than a hundred working days. Buildings and plant would 

 cost 70,000?. to 90,000?., according to the methods and machinery employed. In 

 addition, the site has to be purchased, sidings constructed, and roads made. The 

 cost of the first depends upon local circumstances ; the second, assuming the site 

 to be close to a railway, would probably cost from 3,000?. to 4,000?., and the 

 third from 3?. to 4?. per yard run. The total cost of erecting, equipping, and 

 starting such a factory is computed at 120,000?. Assuming that the farmer is 

 paid 18s. per ton for his beet, and that the factory effects a sale of 5,000 tons of 

 granulated sugar at 14?. per ton, 5,000 tons of dried slices at 5?. per ton, and 

 375 tons of molasses at 3?. 15s. per ton, an estimated profit is arrived at of 

 roughly 31,000?., or 25 per cent, upon the capital invested. 



3. The Fixation of Nitrogen by Free Living Soil Bacteria. 

 By Professor W. B. Bottomley, M.A. 



Since the discovery of the Azotobacter group of nitrogen-fixing organisms by 

 Beijerinck in 1901 numerous attempts have been made, but with little success, 

 to utilise these organisms for increasing the store of soil nitrogen. Gerlach and 

 Vogel (1902) and Freudenreich (1903) obtained negative results in soil experi- 

 ments. Lipman (1904), experimenting with Az. Beijerincki and Az. Vinelandii, 

 found that out of ten experiments there was a loss of nitrogen in every case but 

 one, and this showed a gain of only 4 mgs. 



Certain results from inoculation experiments on clover with oats in 1907, and 

 the discovery that species of Azotobacter and Pseudomonas are always found in 

 association in the algal zone of the root-tubercles of Cycas, suggested that a 

 mixed culture of these organisms might be effective in fixing nitrogen in the soil. 

 Pure cultures of the organisms obtained from Cycas root-tubercles incubated 

 for fifteen days at 24° C. gave the following : — 



Mgs. N. per unit 



Carbohydrate 



per 100 e.c. 



Control 0-48 



Azotobacter 0"56 



Pseudomonas 0"91 



Azotobacter + Pseudomonas 1*24 



Hence Azotobacter and Pseudomonas fix more nitrogen per unit of carbo- 

 hydrate when grown together than when grown separately. Further investigation 

 snowed that this increased fixation applied also to Azotobacter and Pseudomonas 

 from ordinary soil and leguminous nodules respectively. Pure cultures grown in a 

 solution consisting of mannite, 0"5 grm. ; maltose, 0'5 grm. ; potassium phosphate, 

 0.1 grm.; magnesium sulphate, 0.02 grm. per 100 c.c. of water, at 24° C. for ten 

 days, gave the following averages : — 



Mgs. N. per 

 100 c.c. 



Control 053 



Azotobacter 2 - 19 



Pseudomonas 2 - 30 



Azotobacter+ Pseudomonas 4 - 51 



Owing to the different cultural conditions prevailing in soil and culture solu- 

 tions an attempt was made to acclimatise the pure cultures to ordinary soil 

 conditions. About fourteen pounds of autoclaved garden soil was well moistened 

 with the mixed culture and incubated for twenty-one days at 24° C. A culture 



