Bacteria of the Digestive Apparatus 83 



cillus mesentericus rubra, B. mesentericus vulgatus, B. 

 mesentericus fuscus, Bacillus fuscus, a yellow bacillus, 

 probably B. gingival pyogenes (Miller), and Bacillus lique- 

 facium motilis. C. Those that produce pigment, including 

 the same organisms as group B. In carious dentine two 

 organisms, Streptococcus brevis and Bacillus necrodentalis, 

 were invariably present. 



The extinction of the great number of bacteria entering 

 the mouth is referred by most bacteriologists to a bac- 

 tericidal action of the saliva. 



The stomach seems to retain very few of the many 

 bacteria that must enter it, its persistently acid contents 

 being inimical to their development. Certain sarcina, 

 especially Sarcina ventriculi, may be found without any 

 considerable departure from the normal state. In carcinoma 

 and other forms of pyloric obstruction with dilatation, the 

 bacterial flora increases, and in achlorhydria micro-organ- 

 isms of fermentation make their appearance. They are, 

 however, accidental and not permanent tenants of the organ. 



In carcinoma of the stomach a bacillus, probably one of 

 the lactic acid groups, early makes its appearance and is of 

 some diagnostic importance. It is called after its discoverer 

 the Oppler-Boas bacillus,* also on account of angulations 

 found in its threads, Bacillus geniculatus. It is a large 

 bacillus, tending to form long threads easily seen without an 

 oil-immersion lens. It is probably non-motile, does not 

 form spores, stains by Gram's method, and is said by Emory f 

 to divide longitudinally as well as transversely. This, as 

 he says, will, if proved to be correct, be a most important 

 means of identifying the species. Cultures are easily made 

 in media acidified with lactic acid. 



The intestine receives such micro-organisms as have 

 survived whatever destructive influences the gastric juices 

 may have exerted, and its alkaline contents, rich in proteins 

 and carbohydrates in solution, are eminently appropriate for 

 bacterial life. The flora of the intestine is, therefore, in- 

 creased in number and variety of organisms as we descend 

 from its beginning to its end. In the small intestine there 

 may be no bacteria in the upper part of the jejunum, but 

 in most cases Bacillus lactic aerogenes and bacilli of the 

 colon groups are found. These increase in number as the 



*" Deutsche tned. Wochenschrift," 1905, No. 5. 

 t "Bacteriology and Hematology," p. 114. 



