FERMENTATION IN THE INTESTINE. 



279 



Fig. 202. 



divided contained a watery secretion. Perhaps the secretion which occurs after section of the 

 mesenteric nerves is a paralytic secretion. The secretion of the intestinal and gastric juices is 

 diminished in man ill certain nervous affections (hysteria, hypo- 

 chondriasis, and various cerebral diseases) ; while in other condi- 

 tions these secretions are increased. 



Excretion of Drugs. If an isolated intestinal fistula be made, 

 and various drugs administered, the mucous membrane excretes 

 iodine, bromine, lithium, sulphocyanides, but not potassium ferro- 

 cyanide, arsenious or boracic acid, or iron salts. 



In sucklings, not unfrequently a large amount of acid is formed, 

 when the fungi in the intestine split up milk-sugar or grape-sugar 

 into lactic acid (Leube). Starch changed into grape-sugar may 

 undergo the same abnormal process ; hence, infants ought not to 

 be fed with starchy food. 



[Fate of the Ferments. Langley is of opinion that the digestive Scheme of Moreaii s expen- 

 ferments are destroyed in the intestinal canal ; the diastatic fer- ment (Mwmw/)* 



ment of saliva is destroyed by the free HC1 of the gastric juice ; pepsin and rennet are acted 

 upon by the alkaline salts of the pancreatic and intestinal juices, and by trypsin ; while the 

 diastatic and peptic ferments of the pancreas disappear under the influence of the acid fermenta- 

 tion in the large intestine. ] 



184. FERMENTATION IN THE INTESTINE. Those processes, which 

 are to be regarded as fermentations or putrefactive processes, are quite different from 

 those caused by the digestive enzymes or ferments just considered. The putre- 

 factive changes are connected with the presence of lower organisms, so-called 

 fermentation- or putrefaction-producers : and they may develop in suitable media 

 outside the body. The lowly organisms which cause the intestinal fermentation 

 are swallowed with the food and drink, and also with the saliva. When they 

 are introduced, fermentation and putrefaction begin, and gases are evolved. 



Intestinal Gases. During the whole of the foetal period, until birth, fermenta- 

 tion cannot occur ; hence gases are never present in the intestine of the newly-born. 

 The first air-bubbles pass into the intestine with the saliva which is swallowed, even 

 before food has been taken. The germs of organisms are thus introduced into the 

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

 gases goes hand-in-hand with the fermentations. Air is also swallowed, and an 

 exchange of gases take place in the intestine, so that the composition of the in- 

 testinal gases depends upon various conditions. Kolbe and Ruge collected the gases 

 from the anus of a man, and found in 100 vols. : 



1. Air-bubbles are swallowed with the food. The O is rapidly absorbed in the 

 intestinal tract, so that in the lower part of the large intestine, even traces 

 of O are absent. In exchange, the blood-vessels in the intestinal wall give off C0 2 

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

 from the blood. 



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

 fermentation, which takes place even in the small intestine. 



Fungi. The chief agents in the production of fermentations, putrefaction, and other similar 

 decompositions are undoubtedly the group of fungi called schizomycetes. They are small uni- 

 cellular organisms of various forms globular, micrococcus; short rods, bacterium; long rods, 

 bacillus ; or spiral threads, vibrio, spirillum, spirochseta (fig. 23). 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 microscopic organisms take certain constituents 

 from the " nutrient fluids " in which they live, and use them partly for building up their own 



