Nutrition Investigations. 265 



in number during their passage through the digestive tract, and there- 

 fore concludes that they play a very inconsiderable role in the decom- 

 position of cellulose. According to Van Iterson (81), certain aerobic 

 bacteria, attacking cellulose, form from it products which nourish 

 other forms {spirilla); certain anaerobes are also shown to attack 

 it. Eberlein (38), finding in the first stomach of herbivora Infusoria 

 which utilize cellulose for food, suggests that these protozoa, digested 

 farther along in the alimentary tract, serve as means of transforma- 

 tion of cellulose into products which the animal can digest; but there 

 is nothing to indicate that such forms occur in sufficient numbers 

 to be worthy of much consideration. 



Since 1906 three investigators have given the problem careful at- 

 tention. Scheunert (68) has concluded from experiments in vitro that 

 bacteria play an exclusive role in the solution of crude fiber in the coe- 

 cal contents of horses, swine, and rabbits. He found that filtered 

 coecal fluid acted on cellulose much less than unfiltered or simply 

 strained coecal contents. This is contrary to the opinion of Hof- 

 meister (45) and Holdefleiss (48), who attribute the phenomenon to 

 the action of enzymes, and explain the loss of power occasioned by 

 filtering as due to the effect of exposure to the air upon the enzymes. 

 Lohrisch (57) has reported that fresh coecal fluid is effective in destroy- 

 ing cellulose while heated fluid is not. On the other hand, implanting 

 the sterilized fluid with coecal bacteria and protozoa would not restore 

 its activity. Coecal fluid kept at 38° C. any length of time gradually 

 lost its celliflose-dissolving power, while that kept on ice remained 

 active, v. Hoesslin and Lesser (47) have attempted to explain these 

 apparent contradictions, and conclude from their own experiments 

 that anaerobic bacteria are the most effective agents in cellulose de- 

 composition in the intestine. Equal volumes of non-sterilized and 

 sterilized coecal fluid of the horse, to which weighed amounts of cel- 

 lulose had been added, were suspended in sterile physiological salt solu- 

 tion under practically anaerobic conditions and digested for periods of 

 from 9 to 35 days. The disappearance of cellulose with the non-sterfl- 

 ized coecal fluid amounted to from 55.7 per cent to 71.2 per cent; with 

 sterilized fluid, to from 6.2 per cent to 42.4 per cent. It was also found 

 that the addition of 1-5 grams of dextrose would effectively protect 

 the ceUulose from digestion by the non-sterilized fluid, the bacteria 

 preferring the more easily attacked carbohydrate. The gases evolved 

 in these fermentations were characteristic of bacterial action, being 

 chiefly methane, carbon dioxide, and hydrogen. The retarding effect 

 of exposure to the air is explained by the theory that anaerobes are 



