10 Chemistry of the Contents of the Alimentary Tract, SfC 



stomach in large amount, none in the duodenum or jejunum, and 

 traces in the lower sections of the bowel. Peptones were present 

 in traces in the contents of the stomach and jejunum and in the 

 parts "below it. 



General Conclusions. 



1. The contents of the intestinal canal in the dog and calf, 

 and probably in man, are acid in reaction throughout ; the acidity 

 being due to organic acids formed by micro-organisms, hydrochloric 

 acid in combination with proteids and proteid derivatives, and to 

 acid salts. 



2. When the food passes from the stomach into the duodenum it 

 rapidly becomes more concentrated from absorption of water, and 

 consequently more acid ; it still contains a large proportion of 

 hydrochloric acid in combination with proteid bodies, but the 

 increased proportion of inorganic chlorides indicates that this acid 

 is rapidly being acted on by the soda of the pancreatic secretion. 



3. The organisms present in the bowel are divisible into two great 

 groups, those which are able to give the medium in which they grow 

 an acid reaction, and those which cause it to become alkaline or 

 neutral. The first class, as a class, are usually unable to liquefy 

 gelatine. The second class can do so, and form the ordinary putre- 

 factive organisms. These classes are mutually antagonistic. If the 

 number of acid-forming organisms be in large proportion to the total 

 number present, the second class of bacteria fails to grow in any 

 luxuriance, and the intestinal contents do not putrefy in the ordinary 

 sense of the word. Per contra, should the liquefying and alkali- 

 forming organisms be in the majority, the first class is less numerous, 

 and intestinal putrefaction may be present. As, however, the 

 diminished acidity which follows the growth and action of the second 

 class of bacteria is favourable for the multiplication of members of 

 the first class, sufficient acid is formed by them in ordinary cases to 

 neutralise the alkali, and generally to cause the reaction to remain 

 acid. The ammonia formed by the second class often unites with 

 the lactic acid produced by the first, creating, in fact, a salt which 

 is very advantageous for the further development of both classes. 



4. A normal acidity of the stomach contents with the presence 

 of free HC1, or an increased amount of each of these factors, 

 causes a greater destruction of the alkali-forming or putrefactive 

 bacteria than of the acid-forming and more resistant organisms. 

 This naturally leads to diminished decomposition in the bowel. A 

 diminished gastric acidity, or a large meal chiefly proteid in 

 character, allows a larger number of the second class of bacteria to 

 reach the bowel, and may thus cause intestinal decomposition and 

 indigestion, .^ut such a result is not invariable, as the diminished 



