98 LABORATORY BACTERIOLOGY 



EXERCISE XLIX 



THE BACTERIA OF THE MOUTH 



148. In studying cultures from the throat of diphtheritic 

 individuals one encounters many variations in the species of 

 bacteria other than those of diphtheria which are present. The 

 same condition holds true with the microscopic examination of 

 sputum for the tubercle bacteria. The fact has been deter- 

 mined that the organism of lobar pneumonia is often found 

 in the human saliva, and, furthermore, the bacterium of swine 

 plague {Bacterium septiccemim hemorrhagicce) is often in the 

 upper air passages of a large percentage of healthly swine and 

 a like organism in cattle, cats, and dogs. In order, however, 

 to isolate them, it is usually necessary to resort to rabbit inocu- 

 lation. 



Much attention has been given to the study of the bacteria 

 of the mouth, and it seems desirable that a few examinations 

 should be made for the purpose of learning something definite 

 concerning the variety of species which are normal inhabitants 

 of, and which seem to be somewhat localized in, the oral cavity, 

 and consequently which may be encountered in seeking for 

 pathogenic forms. In addition to those forms, which seem to 

 be more or less localized on the mucosa of the^ mouth, there is 

 usually present in the oral cavity a large and changing variety 

 of bacteria which have been introduced with the food. 



References. — Vlcentini, Bacteria of the Sputa, London, 1897. 

 Miller, Die Mikro-organismens des Mundhole, Leipsic, 1889. 

 David, Las Microbes de la Bouche, Paris, 1890. 



149. Work for this Exercise. — Examine carefully and de- 

 scribe fully the cultures made from sputum at the last exercise. 



Make a hanging-drop preparation from one of each of the 

 different kinds of colonies and describe the appearance of the 



