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tat in the mouth, where the conditions as to temperature, moisture, 

 and presence of organic pabulum are extremely favorable for their 

 development. A minute drop of saliva spread upon a glass slide, 

 dried, and stained with one of the aniline colors, will always be 

 found to contain an immense number of bacteria of various forms. 

 Some of these are attached to epithelial cells and some scattered about 

 singly or in groups. Among those seen in a single specimen we will 

 usually find cocci in tetrads, in chains, and in irregular groups, 

 bacilli of various dimensions, and occasionally spirilla. According 

 to Prof. Miller, of Berlin, the following species almost invariably 

 occur in every mouth : Leptothrix innominata, Bacillus buccalis max- 

 imus, Leptothrix buccalis maxima, lodococcus vaginatus, Spirillum 

 sputigenum, Spirochaate dentium. All of these fail to grow in ordi- 

 nary culture media. Miller has made extended attempts to obtain 

 cultures by varying the medium used and attempting to imitate as 

 nearly as possible the natural medium in which they are found; but 

 his attempts have been unsuccessful, or nearly so " only line cultures 

 afforded a limited growth, but the colonies never developed more 

 than fifteen to twenty cells, and a transference to a second plate 

 proved futile, no further growth taking place." 



Up to the year 1885 Miller had isolated twenty-two different 

 species of bacteria from the human mouth. Ten of these were cocci, 

 five short bacilli, six long bacilli, and one a spirillum. Later the 

 same author cultivated eight additional species. Vignal has isolated 

 and described seventeen species obtained by him in pure cultures 

 from the healthy human mouth; most of these are bacilli, and Miller, 

 who found micrococci to be more numerous, supposes the difference 

 in results to be due to the fact that many of the cocci do not grow in 

 nutrient gelatin, which was the medium employed by Vignal. In 

 the researches of the last-named author the following species were 

 obtained most frequently, in the order given: 1. Bacterium termo. 

 2. Bacillus e (Bacillus ulna ?). 3. Potato bacillus. 4. Coccus a. 5. 

 Bacillus b. 6. Bacillus d. 7. Bacillus c (Bacillus alvei ?). 8. Bacil- 

 lus subtilis. 9. Staphylococcus pyogenes albus. 10. Staphylococcus 

 pyogenes aureus. 



Among the species above enumerated we find two of the most 

 common pus cocci, Staphylococcus albus and aureus. but no mention 

 is made of another important pathogenic micrococcus which is fre- 

 quently found in the healthy human mouth, viz., the micrococcus of 

 sputum septicaemia, first named by the writer Micrococcus Pasteuri. 

 This does not grow at ordinary temperatures, and consequently 

 would not be obtained in gelatin plate cultures. Very different re- 

 sults have been reported by different observers as to the frequency 

 with which the pathogenic cocci are found in the buccal cavity. 



