The fermentation of cellulose in vitro by organisms from the rumen of sheep.

The suggestion that micro-organisms are responsible for the decomposition of cellulose in the alimentary canal (Wildt, 1874; Zuntz, 1879; Duclaux, 1882) arose from the proof (Henneberg & Stohmann, 1860-4) that it is, in fact, cellulose which disappears during the pa#sage of crude fibre through the animal (Haubner, 1855). Tappeiner (1882, 1883, 1884, 1888), who was the first to investigate the fate of cellulose, found that paper pulp and cotton wool, when incubated under anaerobic conditions with the fluid contents of the rumen, dissolved slowly with the evolution of methane and carbon dioxide and the formation of fatty acids. He ascribed little nutritional value to the fatty acids, however, and suggested that the fermentation of cellulose was important only because it allowed the digestive enzymes access to the contents of the plant cells (Tappeiner, 1884). This view was not accepted (Henneberg & Stohmann, 1885); the fact that only traces of fatty acids appear in the excreta (Wilsing, 1885; von Knieriem, 1885) implies at least that they are absorbed and oxidized. There was already positive evidence ofthe nutritional value of cellulose (von Knieriem, 1885; Lehmann, 1889). Apart from the investigations of Markoff (1911, 1913) which added little to the information provided by Tappeiner (1884) this aspect of ruminant digestion was abandoned in a state of considerable confusion.