152 MANUAL OF BACTERIOLOGY. 



The staphylococcus pyogenes aureus, the streptococcus 

 pyogenes, the bacillus pyocyaneus and the bacillus coli 

 communis sometimes occur on the skin. According to 

 Welch, it always contains the staphylococcus epidermidis 

 albus, which may be a form of the staphylococcus pyogenes 

 albus. This organism is of some importance to surgeons 

 on account of its relation to the cleansing of the skin before 

 operations. It seems impossible, by any amount of clean- 

 ing, to dislodge all of the germs in the skin, especially 

 those under the nails. 



The bacteria of the exposed mucous membranes like the 

 conjunctiva and the nasal cavity 1 and the mouth cavity will 

 naturally be very fluctuating both in quantity and quality; 

 they will be, in fact, those which happen to fall upon the 

 surface or to be drawn in from the external air. 



In the mouth, however, there is a certain group of organ- 

 isms more or less characteristic of it, many of which have 

 not been successfully cultivated. These have been thor- 

 oughly studied by Miller, to whose works students are re- 

 ferred. 2 



Several species of spirilla have been discovered in the 

 mouth and are found along the margins of the gums. The 

 leptothrix buccalis, and related organisms which have a 

 long, ribbon-like form, also occur in the mouth. The mi- 

 crococcus lanceolatus (or pneumococcus) appears to be 

 present in many human mouths. In 15 to 20 per cent, of 

 human mouths this organism is sufficiently virulent to pro- 

 duce fatal septicemia when inoculated into susceptible ani- 

 mals. Pyogenic bacteria, especially streptococci, occur fre- 

 quently, although not regularly, in the mouth. Putrefactive 



1 Hasslauer, " Die Bakterien flora der gesunden und kranken Nasen- 

 schleimhaut," L'cntralb'.utt f. Bakteriologic, Vol. XXXIII., 1902, Orig. 

 p. 47. 



- Miller, " Microorganisms of the Mouth." For a recent review on 

 the bacteria of the month, see Madzar, Ccntralblatt f. Bakteriologic, Vol. 

 XXXi, 1902, Ref. p. 489; Vol. XXXII., p. 609. 



