104 INFECTIONS OF THE DIGESTIVE TRACT 



bacilli of typhoid fever, of dysentery, and of B. pyocyaneus 

 probably hold equally true of the more saprophytic forms, 

 such as the microorganisms concerned in chronic exces- 

 sive intestinal putrefaction. It is certain that the intes- 

 tine may harbor considerable numbers of B. putrificus 

 and B. aerogenes capsulatus or both of these together 

 without the development of clinical manifestations. A 

 variety of conditions may be presumed to so favor the 

 development of these anaerobes that their products, 

 instead of being formed in such small amounts as to 

 be harmless, begin to exert a detrimental effect upon 

 the organism. Especially important in this connection 

 are influences which alter the character of the secretions 

 in the large intestine or bring into the large intestine 

 unusually large quantities of partly digested proteid food. 

 There is an important practical aspect to the fact 

 that pathogenic organisms inhabit the intestinal tract 

 without giving obvious clinical signs of their presence. 

 A good quality of milk or meat, free from pathogenic 

 bacteria, may be blamed for bacterial decompositions of 

 a harmful kind which are in reality due to abnormal bac- 

 terial conditions prevailing in the digestive tract before 

 the use of the food under suspicion. In certain con- 

 ditions of the digestive tract an excessive or even a 

 moderate meal of proteid food will precipitate an intoxi- 

 cation or a seizure of vomiting or diarrhoea. There 

 are cases classed as "ptomaine poisoning" in which the 

 digestive tract, rather than the food, is responsible for 

 the observed disorders. 



