SOIL CONDITIONS AND PLANT GROWTH 



more nitrogen than Clostridium per grm. of sugar decom- 

 posed. 



The nature of the compound is also important. Table 

 LIII. gives the amounts of nitrogen fixed per grm. of com- 

 pound decomposed. 



Table LIII. — Mgms. of Nitrogen Fixed by Azotobacter per Grm. of 

 Substance Decomposed,^ Lohnis and Pillai (i8irf). 



Mg. of Nitrogen 

 Fixed. 



7-5 to 10 



5 to 7-5 



2-5 to 5 



I to 2*5 



Nil 



Mannitol, xylose, lactose, laevulose, inulin, galactose, maltose, 



dextrin, sucrose + calcium carbonate. 

 Sucrose alone, dextrose, sodium tartrate + calcium carbonate, 



glycerol + calcium carbonate. 

 Starch, sodium tartrate, sodium succinate, calcium lactate. 

 Sodium propionate, sodium citrate, glycerol alone. 

 Calcium butyrate, potassium oxalate. 



Little is known of the chemistry of the process, even the 

 fate of the sugar has not been definitely ascertained. The 

 only obvious product is carbon dioxide, fatty acids being 

 formed only in small quantities, in sharp contrast with 

 Clostridium. 



Starting with 15-9 grms. of dextrose Stoklasa (275/^) re- 

 covered 7*9 as carbon dioxide, 0*3 as ethyl alcohol, 0-2 as 

 formic acid, 07 as acetic acid, 0*2 as lactic acid, but could not 

 trace the remaining 6-5 grms, 



^ For list of other substances see F, A. Mockeridge, Biochem. Journ., 1915 

 g, 272-283. 



2 The sugar was not all used up in this experiment. 



