82 Infection 



invariably present upon the human skin, and must be re- 

 garded as habitual parasites. 



Where the skin is peculiar in its moisture and greasiness, 

 however, additional forms are found. Thus, in preputial 

 smegma, in the axillae, and sometimes about the lips and 

 nostrils, a bacillary organism, Bacillus smegmatis, is invari- 

 able, and the recent work by Schaudinn and Hoffman* has 

 shown that the skin of the genitalia harbors a spiral organism 

 which they call Spirochseta refringens. 



In the external auditory meatus a coccus, Micrococcus 

 cereus flavus, is almost always to be found in the waxy 

 secretion. 



Upon the conjunctiva as many accidental organisms may 

 be found as shall have been caught by its moist surface, 

 though the researches of Hildebrand and Bernheim and 

 others seem to show that the tears have some antiseptic 

 power and prevent the organisms from growing, so that in 

 health there are very few permanent residents of the sac, 

 certain cocci seeming to be the only constant forms. 



The mouth has been carefully studied bacteriologically 

 by Miller, f who found six organisms Leptothrix innomi- 

 nata, Bacillus buccalis maximus, Leptothrix buccalis 

 maxima, lodococcus vaginatus, Spirillum sputigenum and 

 Spirochaeta dentinum (denticola) in every mouth. Prac- 

 tically the same conclusions were reached by Vincentini. J 

 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. 



From the mouth these organisms may be traced into the 

 pharynx and esophagus. 



In studying the micro-organisms of dental caries Goodby 

 found a large number of organisms which he divided into 

 three groups: A. Those that produce acids, including 

 Streptococcus brevis, Bacillus necrodentalis (Goodby), 

 Sarcina alba, Sarcina lutea, Sarcina aurantiaca, Staphylo- 

 coccus pyogenes aureus, and Staphylococcus pyogenes sali- 

 varius (Biondi). B. Those that liquefy blood-serum: Ba- 



* "Deutsche med. Woch.," May 4, 1905. 

 t "Micro-organisms of the Human Mouth," Phila., 1890. 

 % "Bacteria of the Sputa and Cryptogamic Flora of the Mouth," 

 London, 1897. 



Transactions of the Odontological Society, June, 1899. 



