BACTERIAL FERMENTATION IN THE INTESTINES. 329 



fluid. This result is explained in part by paralysis of the vasomotor nerves of 

 the intestinal tract. As the nerve-filaments for a limited portion of intestine, 

 ligated in two places, can be completely separated, the watery intestinal contents 

 will be found only in the corresponding loop of intestine. According to Hanau, 

 the condition in this experiment of Moreau is one of paralytic secretion, which, 

 with regard to time, pursues a typical course. 



The following substances are after ingestion excreted by the intestinal mucous 

 membrane of isolated fistulas : iodin, bromin, lithium, metallic ferrocyanogen, salts 

 of iron and others. 



FERMENTATIVE PROCESSES IN THE INTESTINES DUE TO 

 MICROBES; INTESTINAL GASES. 



Wholly different from the peculiar digestive processes just described, 

 which are brought about by definite unorganized ferments or en- 

 zymes, are those processes which are to be considered as fermentative 

 or putrefactive decompositions. These are caused by microbes, the so- 

 called excitants of fermentation or putrefaction, or organized ferments; 

 and they may, therefore, take place outside of the body, in suitable 

 media. Lower forms of organisms, which maintain fermentative pro- 

 cesses in the intestinal tract, are often swallowed with food and drink, 

 as well as with the buccal fluid. Upon the introduction of these the 

 processes of decomposition begin, with simultaneous production of gas. 

 On a pure milk-diet intestinal putrefaction is much less marked. 



Fermentation, therefore, cannot occur in the intestine during fetal 

 life. For this reason gases are always absent in the intestine of 

 the new-born. The first bubbles of air reach the intestine through 

 frothy saliva swallowed, even before food is taken. As, however, micro- 

 organisms may enter the intestinal tract with the air swallowed, the 

 development of gas by fermentation must soon follow. The development 

 of the intestinal gases thus goes hand in hand with the fermentative 

 processes. As, however, gases from the air swallowed are exchanged in 

 the intestinal canal, the composition of the intestinal gases will be found 

 to be dependent upon various factors. 



Kolbe and Ruge collected intestinal gases from the human anus and 

 found in 100 volumes: 



Food. C0 2 . H. CH4. H,S. 



Milk ................. 16.8 43-3 -9 



Meat ................ -.4 ai 



Peas ................. 21.0 4.0 55.9 



3.3 ) 

 18.9 ) 



Moreover, it should be noted: i. That oxygen is rapidly absorbed by 

 the walls of the canal from the air-bubbles swallowed with the food, so 

 that, in the lower part of the large intestine, even traces of oxygen are 

 absent. In exchange the blood-vessels of the intestinal wall give up 

 into the intestine carbon dioxid, so that, therefore, a portion of the car- 

 bon dioxid in the intestines is derived from the blood by diffusion. 



2. Hydrogen, carbon dioxid and ammonia, as well as marsh-gas, are 

 also developed from the intestinal contents by fermentation, which may 

 take place even in the small intestine. 



Bacteria as Excitants of Fermentation. The organisms that especially cause 

 fermentation, putrefaction and other forms of decomposition are bacteria (schizo- 

 mycetes), namely, minute, unicellular structures, chiefly having the shape < 

 sphere (micrococcus) , or a short rod (bacterium) , or a long rod (bacillus) , or a 

 spiral thread (vibrio, spirillum, spirochasta) . Their power of reproduction is 

 beyond all conception. Through their vital phenomena they cause profound 



