322 DISTRIBUTION OF BACTERIA 



plan tubes, and bladder in healthy individuals contain no 

 bacteria. 



The secretions of the female genito-urinary tract at certain 

 times seem to be slightly germicidal. For example, in the 

 later stages of pregnancy and at parturition in the healthy 

 person very few bacteria, if any, are found on the surfaces 

 which come in contact with the secretions. The species 

 found are usually non-pathogenic. Under certain conditions 

 the genito-urinary organs of the male and female may be 

 subjected to severe infections. 



Bacteria of the Nose. The mucous membrane of the nose 

 usually contains a great variety and a large number of bac- 

 teria. They are derived principally from the inspired air. 

 The hairs and mucous secretions of the nose and upper res- 

 piratory passages catch the bacteria, and as a result practically 

 none reach the alveoli of the lungs immediately. Conse- 

 quently the expired air is usually sterile. The nasal mucus 

 exerts a very slight germicidal action on some bacteria. 

 Pathogenic bacteria, such as Bact. diphtherias and M. pneu- 

 moniae, are frequently found on some normal nasal mucous 

 membranes. The nose and mucous secretions of diseased 

 individuals often contain pathogenic bacteria. This is some- 

 times the case in individuals suffering from tuberculosis and 

 other infectious diseases. 



Bacteria of the Mouth. A large amount of work has been 

 done upon the bacteria which are usually present in the 

 mouth. The mouth is lined by a mucous membrane com- 



