MORPHOLOGY AND^ PHYSIOLOGY 331 



In his work, the following medium was used: 



Potassium phosphate l"gm. 



Magnesium sulphate 1 ' 



Ammonium sulphate 1 



Sodium chlorid trace 



Distilled water 1000 c.c. 



In some cases he replaced the ammonium salt with 0.5 per cent, 

 asparagin, 1 per cent, peptone, or 0.5 per cent, beef extract. The 

 solutions were placed in flasks containing filter paper and then 

 inoculated. Inasmuch as the incubation period of cellulose fer- 

 mentation is long and variable, he found it best to seed with con- 

 siderable of the organism. Ordinarily, this was done by taking 

 a small piece of the decomposing paper from an old culture. 



Soon after inoculation there was observed a slight turbidity 

 in the flasks. Then the paper thickened and assumed a decayed 

 appearance. It was covered with little specked places where it 

 had been decomposed by the organisms. This latter, appearance 

 varied; at times the holes were large and few, and at other times 

 they were small and very numerous. At still other times the 

 paper seemed to thicken and then to fall to pieces. At the end of 

 the process there remained a residue entirely different from the 

 original paper. In old cultures the white appearance of the paper 

 had disappeared and it had taken on a yellowish brown color, 

 which often appeared even in the surrounding solution. The 

 gases given off had the odor of decayed cheese. At the height of 

 the process particles of filter paper were carried to the surface of 

 the liquid by the gas. The above description applies to the process 

 as brought about by both the hydrogen and methane organ- 

 isms which Omelianski succeeded in isolating in pure cultures by 

 the method of repeated heating (75 C. for fifteen minutes), which 

 is based on a difference in the life history of the two organisms. 

 The methane fermentation organism develops more rapidly than 

 the other variety and gains the supremacy in the early stages of 

 the process. If heat be applied at this stage the more slowly germi- 

 nating spores of the hydrogen-fermenting organism, being in a 

 resistant stage, survive^ 



Morphology and Physiology. A microscopic examination of the 

 hydrogen ferment reveals the following: In the young culture the 

 bacillus is about 0.5 IJL in width and from 4 to 8 /z in length. In 

 old cultures they are from 10 to 15 IJL in length. They never occur 

 linked together in chains but appear as slightly bent rods. "Err 

 still older cultures they take the drumstick form which gradually 

 develops into a round spore about 1.5 IJL in diameter. They are 

 readily stained by the anilin dyes. In old cultures they give the 

 characteristic colors for the spore and surrounding sheath with 

 carbol-fuchsin and methylene blue. They are not stained blue 



