570 A MANUAL OF BACTERIOLOGY 



Nose. In the anterior nares crusts and vibrissae micro-organisms 

 are present in great abundance, but, contrary to the usual opinion, 

 StClair Thomson and the writer l showed that the mucous mem- 

 brane of the interior of the nose is comparatively sterile, and when 

 organisms are present they are very scanty compared with the 

 number of organisms inspired. 2 Moreover, organisms artificially 

 deposited were found to be rapidly disposed of. After two hours, 

 for example, prodigiosus inoculated on to the inferior turbinate 

 could not be detected by cultivation. Wurtz and Lermoyez 

 asserted that the nasal mucus is germicidal, but StClair Thomson 

 and the writer 3 were unable to confirm this, though it may have 

 an inhibitory action. 



Air-passages. Below the larynx under normal conditions the 

 air-passages are free from micro-organisms. Expired air is also 

 free from organisms, and the air from the naso-pharynx after passing 

 through the nasal cavities is deprived of the majority of its 

 organisms. 4 



Mouth. Micro-organisms of all kinds are present in the buccal 

 cavity in the greatest abundance leptothrix, bacilli, pyogenic 

 cocci, sarcinae, and spirilla are almost always to be found. The 

 Streptococcus pyogenes, M. pyogenes, var. aureus, and Streptococcus 

 pneumonice are frequently present. Certain organisms have their 

 normal habitat in the mouth, are difficult to cultivate, and are of 

 considerable importance in the production of dental caries. 5 Well- 

 defined micrococci and streptococci also occur in the saliva (M. 

 salivarius, p 231, and 8. salivarius, p. 234). The normal saliva is 

 germicidal to some extent. (See also p. 460.) 



Stomach and intestine. Although a vast number of organisms 

 gain access to the stomach, a large number are destroyed by the 

 acid gastric juice. At the same time a considerable proportion 

 are able to survive sarcinae, and lactic and butyric acid bacilli. 

 In normal nurslings the mouth and stomach contain few bacteria 

 a few cocci, and some bacilli of the B. coli and B. lactis aerogenes 

 groups. The small intestine contains remarkably few organisms 

 of the same types. In the large intestine bacteria are extremely 

 numerous, particularly Gram-positive ones. These are mostly 



1 Medico-CMrurg. Trans., vol. Ixxviii, 1895 (Bibliog.). 



2 Other observers, however, have not altogether confirmed this. 

 See Iglauer, Laryngoscope, 1901, November, p. 363. 



3 " The Fate of Micro-organisms in Inspired Air," Lancet, 1896 

 January 11. 



4 Ibid. 



5 See Goadby, Mycology of the Mouth. 



