Micro-Organismal Tenants of the Normal Human Body 73 



Bacillus buccalis maximus, Leptothrix buccalis maxima, lodococcus 

 vaginatus, Spirillum sputigenum and Spirochaeta dentinum (denti- 

 cola) — ^in every mouth. Practically the same conclusions were 

 reached by Vincentini.* These organisms are peculiar in that they 

 will not grow in artificial culture. In addition to this permanent 

 flora, Miller cultivated fifty-two other species, some of which were 

 harmless, some well-known pathogens. 



In studying the micro-organisms of dental caries Goodbyf found 

 a large number of organisms which he divided iato three groups: 

 A. Those that produce acids, including Streptococcus brevis. Ba- 

 cillus necrodentalis (Goodby), Sarcina alba, Sarcina lutea, Sarcina 

 aurantiaca. Staphylococcus pyogenes aureus, and Staphylococcus 

 pyogenes sahvarius (Biondi). B. Those that liquefy blood-serum: 

 Bacillus mesentericus rubra, B. mesentericus vulgatus, B. mesenteri- 

 cus fuscus, Bacillus fuscus, a yellow bacillus, probably B. gingivae 

 pyogenes (Miller), and Bacillus liquefacium motilis. C. Those that 

 produce pigment, including the same organisms as group B. In 

 carious dentine two organisms. Streptococcus brevis and Bacillus 

 necrodentahs, were invariably present. 



The extinction of the great number of bacteria entering the mouth 

 is referred by most bacteriologists to a bactericidal action of the 

 saHva. In addition to the bacteria, representatives of the sac- 

 charomycetes and hyphomycetes, are commonly found in normal 

 mouths. 



Amoebae are also commonly found in the gingival grooves and 

 in the crevices between the teeth. These have been called Amoeba 

 gingivalis and are regarded by some as harmless commensals of 

 the normal mouth, by others as pathogenic parasites responsible 

 for the suppuration of the tooth follicles in pyorrhoea alveolaris. 



The crypts of the tonsils regularly harbor a miscellaneous collec- 

 tion of bacteria, among which staphylococci and streptococci, chiefly 

 of the non-hemolyzing varieties may be found. The unprotected 

 surfaces of the crypts doubtless permit these organisms to penetrate 

 to the deeper lymphatic structures of the neck where they are usually 

 destroyed. 



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 ventricuh, 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-organisms 

 of fermentation make their appearance. They are, however, acci- 

 dental 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 im- 



* "Bacteria of the Sputa and Cryptogamic Flora of the Mouth," London, 1897. 

 t Transactions of the Odontological Society, June, 1899. 



