180 PHYSIOLOGY CHAP. 



scientific acumen they reveal, that the gastric juice kept for long 

 periods in closed vessels does not putrefy, although it gradually 

 loses its antiseptic properties ; that fresh meat steeped in gastric 

 juice keeps for a long time without putrefying ; that putrid 

 meat wholly or partially loses its bad smell in gastric juice, and 

 that the foetid odour disappears in proportion as it is digested, 

 when it is forcibly fed to ravens (attached to a thread by which it 

 can be examined at different intervals) ; lastly, that when en- 

 closed in finely perforated wooden tubes, and introduced into his 

 own stomach, " it lost even the slightest trace of putrescence." 



Modern workers have shown that the process of putrefaction is 

 effected by specific bacteria, and that the antiseptic action of the 

 gastric juice is due to its free hydrochloric acid. In fact Sieber 

 (1879) found that the amount of HC1 necessary to retard the 

 putrefaction of meat is approximately equal to the normal acid 

 content of the gastric juice, and that a 0'5 per cent solution of 

 this acid suffices to hinder the development of the saprophytic 

 bacteria. Miquel (1884) confirmed this observation, and found 

 that the addition of 0'2-0'3 grins. HC1 to 100 c.c. beef-tea 

 prevented it from putrefying. 



The antiseptic and bactericidal power of the gastric juice, of 

 course, has its limits. Some bacteria, particularly in the spore 

 stage, exhibit such resistance to chemical agents that they are 

 only destroyed by hydrochloric acid at a higher degree of concen- 

 tration than that of the gastric juice. Falk (1883) found the 

 latter inadequate to destroy the tubercle bacillus, while it did kill 

 the anthrax bacillus, leaving the spores intact (Perroncito). Ac- 

 cording to Nicati and Eietsch, and to Koch (1884), the cholera 

 bacillus is easily killed by a dilute solution of HC1, so that 

 introduction of this culture into the stomach of an animal does 

 not infect it. On the other hand, infection ensues if the culture is 

 introduced into the small intestine or the stomach, after injection 

 of a soda solution. According to Fermi (1894), the gastric juice 

 has no sterilising action on hyphomycetes and blastomycetes. 

 which therefore develop in it and alter its digestive activity. The 

 bacteria of lactic and butyric acid fermentation also seem to resist 

 the gastric juice, since after ingestion of much carbohydrate there 

 is nearly always a slight fermentation with development of lactic 

 and butyric acid. With abnormal catarrhal conditions of the 

 gastric mucosa, the amount of free HC1 in the gastric juice 

 diminishes in proportion with the increased secretion of the 

 alkaline mucus. Under these conditions all the bacteria that 

 excite fermentation, particularly those of lactic, butyric, and also 

 acetic and alcoholic fermentation, are able to germinate freely in 

 the stomach. In consequence of this fermentation lactic, butyric, 

 and acetic acid and alcohol develop at the expense of the carbo- 

 hydrates ingested. At the same time gases are developed, i.e. 



