BACTERIAL FERMENTATION IN THE INTESTINES. 331 



to their development ; and, finally, that sufficient material of the most varied kind 

 not entirely disposed of by the digestive processes, furnishes nutrient matter for 

 the vegetation of the germs, it is not surprising that a rich formation of these 

 organisms is found in the alimentary canal and that they cause numerous forms 

 o decomposition in the intestinal contents. Knowledge of these processes is 

 at the present time, still highly deficient; and the formula* proposed for the de- 

 compositions can, therefore, only approximately explain the processes. For this 

 reason, the following statements can only be considered provisionally as aphorisms 

 in the study of the mycotic intestinal decompositions. 



Fermentation of Carbohydrates, which takes place principally in the 

 small intestine, i. Bacillus acidi lactici (bacterium lacticum), whose 

 biscuit-shaped ^ cells, from 1.5 to 3 /^ in length, are arranged in groups 

 or rows or are isolated, causes fermentative decomposition of sugar into 



inactive lactic acid : 



C 6 H 12 6 2(C 3 H 6 3 ) 



i Grape-sugar = 2 Lactic acid. 



Milk-sugar (C 12 H 22 O n ) may be decomposed by the same bacterium, with 

 the addition of water, first into two molecules of grape-sugar, 2(C 6 H 12 O 6 ), 

 and this in turn into four molecules of lactic acid, 4(C 3 H 6 O 3 ). 



This micro-organism, whose germs float in the air everywhere, causes the 

 spontaneous souring and curdling of milk. It develops further in sour-crout, 

 sour pickles, and the like. It induces fermentation of cane-sugar, mannite, 

 inosite, and sorbite, as of the sugars mentioned. In addition to lactic acid, 

 carbon dioxid also results. There are, besides, other lactic-acid-producing bacteria 

 that are capable further of transforming starch into sugar, van de Velde 

 obtained lactic, butyric and succinic acids as products of the fermentative activ- 

 ity of the bacillus subtilis (Fig. 123), and mannite as a reduction-product. 



2. Bacillus butyricus, which is often stained blue by iodin in a 

 starch-containing medium, transforms lactic acid into butyric acid, 

 together with carbon dioxid and hydrogen. 



2(C S H 6 3 ) - C 4 H 8 2 + 2CO, + 4 H. 



2 Lactic Acid = i Butyric Acid + 2 Carbon Dioxid + 4 Hydrogen. 



This bacterium (Fig. 122, B) is a true anaerobe, which vegetates only in the 

 absence of oxygen. The lactic-acid bacillus, which actively consumes oxygen, 

 is therefore its natural predecessor. Butyric-acid fermentation completes the 

 transformation of many carbohydrates, chiefly starch, dextrin and inulin. It 

 takes place constantly in the feces. There are a number of other bacteria with 

 similar activity. The butyric-acid bacillus produces also dextrin from starch. 



3. Certain micrococci are capable of developing alcohol as the chief 

 product from sugar. 



In the human small intestine there are present besides: bacterium Bischleri 

 (short rods) , which produces alcohol, inactive lactic acid and acetic acid from sugar; 

 bacterium ilei (short rods), which transforms sugar into alcohol, succinic acid 

 and some active paralactic acid, together with carbon dioxid and hydrogen; 

 bacterium ovale ilei (almost spherical), which transforms sugar into alcohol, 

 paralactic acid and traces of the fatty acids; bacillus gracilis ilei (delicate long 

 rods), which has a similar action; bacterium lactis acrogenes, which transforms 

 sugar into alcohol and succinic acid, together with lactic acid and some acetic 

 acid. 



The presence of yeast also may result in the production of alcohol 

 in the intestine, in both instances likewise from milk-sugar, which at 

 first passes over into dextrose. Only traces are found in the intestine. 



4. Bacterium aceti (Fig. 122, A) is capable, outside of the body, of 

 transforming alcohol into acetic acid. 



C 2 H 6 + O = C 2 H 4 + H 2 



Alcohol + Oxygen = Aldehyd Water. 



