440 PRINCIPLES OF SOIL MICROBIOLOGY 



ing pure filter paper, inoculated with a small quantity of soil and 

 incubated at 60°C, produces gas and a distinct odor. The filter 

 paper is all broken up in 10 to 14 days, with the formation of C0 2 and 

 CH 4 ; formic and acetic acids are also demonstrated among the decom- 

 position products. 38 Kroulik 39 obtained cellulose decomposition at 

 60°C, under aerobic and anaerobic conditions. When cellulose was 

 decomposed aerobically, only C0 2 was formed; under anaerobic condi- 

 tions, the cellulose was decomposed more completely, with the forma- 

 tion of H 2 , C0 2 and even H 2 S. Among the decomposition products, 

 considerable quantities of acetic acid, some butyric, formic and acetic 

 acids were demonstrated. Organic nitrogen was found to be the best 

 source of nitrogen. Pringsheim 40 obtained, under anaerobic condi- 

 tions, out of 3 grams of cellulose decomposed, 0.2125 gram formic acid, 

 1.15 gram acetic acid and a small quantity of lactic acid. Carbon 

 dioxide made up 21.9 to 49.1 per cent of the gases, the rest was hydrogen. 

 Ethyl alcohol, acetic, butyric and lactic acids, hydrogen and methane 

 result from the decomposition of cellulose at higher temperatures. By 

 changing the conditions of growth, the relative amounts of the products 

 may be changed. Viljoen, Fred and Peterson 41 found that, out of 60 

 grams of cellulose added to 4 liters of medium containing 20 grams of 

 peptone, 42 grams were decomposed by thermophilic (anaerobic bac- 

 teria) with the formation of the following products: 



Carbon of cellulose decomposed 18.6 grams 



Carbon of products accounted for 17.0 grams 



Among the gases, hydrogen was formed in considerable quantities, 

 but no methane. 



The rapid heating of hay results from transformation of cellulose 

 and other carbohydrates in the hay by microorganisms. 42 Bad. colt, 



18 MacFayden and Blaxall, 1899 (p. 201). 

 "Kroulik, 1913 (p. 157). 



40 Pringsheim, 1913 (p. 202). 



41 Viljoen, Fred and Peterson, 1926 (p. 202). 



42 Miehe, 1907 (p. 300); Uber die Selbsterhiztung des Heues. Arb. deut. landw. 

 Gesell. H 196, 36 p. 1911; (Centrbl. Bakt. II, 34: 281-282. 1912). 



