DECOMPOSITION OF ORGANIC MATTER IN THE SOIL. 247 



position of cellulose to an organism found by Trecul in decomposing 

 vegetable materials, and named by him Amylobacter in 1865, because of 

 the blue color assumed by it when stained with iodine. 



Subsequent investigations by Omelianski begun in 1894 and continued 

 through a period of years demonstrated the presence of specific anaerobic 

 organisms in decomposing cellulose. He described two distinct species 

 of long, slender bacilli, assuming the clostridium form when in the spore 

 stage. Morphologically the organisms can hardly be distinguished, but 

 physiologically they show important differences in that one causes the 

 fermentation of cellulose with the production of gases consisting of carbon 

 dioxide and methane, while the gases produced by the other consist of 

 carbon dioxide and hydrogen ; hence the one is designated by Omelianski 

 as the methane bacillus and the other the hydrogen bacillus. These 

 organisms do not stain blue with iodine, and do not belong, therefore, to- 

 the butyric bacilli designated as Amylobacter by earlier investigators. 1 

 Omelianski's investigations make it appear that the butyric organisms 

 are not capable of fermenting cellulose proper. 



In culture solutions containing mineral salts and nitrogen in the form 

 of ammonium compounds the decomposition of filter-paper and other 

 forms of cellulose proceeds with considerable rapidity. Calcium carbon-l 

 ate must be added to neutralize the acids formed, otherwise the fermen-\ 

 tation soon comes to a standstill. In one of Omelianski's experiments! 

 begun in October, 1895, and ended in November, 1896, 3.3471 g. of 

 cellulose was decomposed by a nearly pure culture of hydrogen bacilli. 

 The products consisted of 2.2402 g. fatty acids, 0.9722 g. carbon 

 dioxide and 0.0138 g. of hydrogen, a total of 3.2262 g. which nearly 

 accounts for all of the cellulose destroyed. The fatty acids were made 

 up of butyric and acetic acids with a slight proportion of some higher 

 homologue, probably valerianic acid. 



In a similar experiment with an apparently pure culture of the methane 

 bacillus, begun in December, 1900, and ended in April, 1901, fermentation 

 began after an incubation period of about one month, and the entire 

 volume of gas gradually evolved was 552.2 c.c. This mixture consisted 

 of 190.8 c.c. methane and 361.4 c.c. carbon dioxide. The products formed 

 from the 2.0065 g- cellulose consumed included 1.0223 g. fatty acids, 

 0.8678 g. carbon dioxide and 0.1372 g. of methane, or a total of 

 2.0273 g- The slight difference in weight in favor of the fermen- 

 tation products falls within the limit of error. These experiments show 



