CHAPTER X. 



THE CHEMICAL PEOCESSES WHICH HAVE THEIR SEAT 

 IN THE INTESTINES AND WHICH ARE THE RESULTS 

 OF THE ACTIVITIES OF MICRO-ORGANISMS. THE 

 PRODUCTS OF THESE PROCESSES. 



Introductory Remarks. 



WHEN treating of the influence of changes in the acidity of the 

 gastric juice in disease (p. 167 et seq.) its antiseptic action was 

 discussed, and it was shewn that the acid which it contains exerts a 

 marked influence in destroying the putrefactive, as well as many of 

 the pathogenic, organisms which may find their way into the stomach. 

 In the normal condition, gastric digestion in a healthy man is a process 

 which proceeds entirely under the influence of enzymes, and the 

 fermentations which are the results of the activities of organised 

 ferments must be looked upon as a departure from normality as, 

 indeed, pathological. In the small, but much more so in the large, 

 intestine, the conditions are more favourable to the growth of 

 microbes, and hence, side by side of the digestive processes, properly 

 so-called, others are going on which are due to the intervention of 

 imported germs. In the herbivora, the action of organised ferments 

 attains a high importance, seeing that it is apparently through their 

 action that a part of the cellulose is utilised, which forms so large 

 a part of the food consumed. In man and the carnivora, however, 

 organised ferments play a secondary part in the processes of the small 

 intestine, and digestion appears to be most typically physiological 

 when their activity is least conspicuous, and when certain, at least, 

 of the products of that activity are smallest in amount. 



It is customary to speak of the putrefactive processes of the small 

 intestines, but the expression is an inaccurate one. When we open 

 the small intestines immediately after death, we find their contents 

 entirely free from putrefactive odour, properly so called. It is only 

 when we examine the contents of the large intestine that we become 

 aware of the presence of foetid products, which increase in amount as 

 the contents undergo the changes which ultimately result in their 

 transformation into the faeces. There can be no doubt that special 

 influences must be at work to limit, or rather to modify, the putre- 



