372 



FUNGI AS EXCITERS OF FERMENTATION. 



intestinal tract, and give rise to the formation of gases. The evolution 

 of intestinal gases goes hand-in-hand with the fermentations. Atmo- 

 spheric air is also swallowed, and an exchange of gases takes place in 

 the intestine, so that the composition of the intestinal gases depends 

 upon various conditions. 



Kolbe and Kuge collected the gases from the anus of a man, and 

 found in 100 vols. : 



With regard to the formation of gas and the processes of fermenta- 

 tion we note 



1. Air bubbles are swallowed when food is taken. The thereof 

 is rapidly absorbed by the walls of the intestinal tract, so that in the 

 lower part of the large intestine, even traces of are absent. In 

 exchange, the blood-vessels in the intestinal wall give off C0 2 into the 

 intestine, so that a part of the C0 2 in the intestine is derived by 

 diffusion from the blood. 



2. H and C0 2 NH 3 and CH 4 are also formed from the intestinal 

 contents by fermentation, which takes place even in the small 

 intestine (Planer). 



Fungi as Exciters Of Fermentation. The chief agents in the production 

 of fermentations, putrefaction and other similar decompositions are undoubtedly the 

 group of the fungi called Scliizomycetes. They are small unicellular organisms of 

 various forms, globular (Micrococcus), short rods (Bacterium), long rods (Bacillus), 

 or spiral threads ( Vibrio, Spirillum, Spirochceta). The mode of reproduction is 

 by division, and they may either remain single or unite to form colonies. Each 

 organism is usually capable of some degree of motion. They produce profound 

 chemical changes in the fluids or media in which they grow and multiply, and these 

 changes depend upon the vital activity of their protoplasm. These minute micro- 

 scopic organisms take certain constituents from the "nutrient fluids" in which 

 they live, and use them partly for building up their own tissues and partly for their 

 own metabolism. In these processes, some of the siibstances so absorbed and 

 assimilated undergo chemical changes, some ferments seem thereby to be produced, 

 which in their turn may act upon material present in the nutritive fluid. 



These fungi consist of a capsule or envelope enclosing protoplasmic contents. 

 Many of them are provided with excessively delicate cilia, by means of which they 

 move about. The new organisms produced by the division of pre-existing ones, 

 sometimes form large colonies visible to the naked eye, the individual fungi being 

 united by a jelly-like mass, the whole constitiiting zooyloca. In some fungi, repro- 

 duction takes place by spores; more especially when the nutrient fluids are poor 

 in nutritive materials. The bacteria form longer rods or threads which are jointed, 

 and in each joint or segment small (1-2/u) highly refractive globules or spores are 

 developed (Fig. 148, 7). In some cases, as in the butyric acid fermentation, the rods 



