PART III. 



NON-PATHOGENIC BACTERIA. 



THE number of varieties of non-pathogenic bacteria is 

 very large. Eisenberg 1 describes 376 species of bacteria, 

 mostly non-pathogenic. Sternberg 2 enumerates 489 species, 

 including the pathogenic varieties, but the majority, of 

 course, are non-pathogenic. Fliigge 3 considers about 500 

 species of bacteria. Migula 4 recognizes nearly 1,300, and 

 Chester 5 about 800 species. Probably some of the bacteria 

 which have been described as distinct species are in reality 

 not different; but, on the other hand, it is also probable 

 that a still larger number of species have not been described 

 at all ; how many it is impossible to say. In a work of this 

 character it is feasible to mention only a few of the com- 

 monest and best-known species of non-pathogenic bacteria. 



Micrococcus agilis. Found in water; coccus about i p 

 in diameter, usually appearing as diplococci, sometimes as 

 streptococci and tetrads ; liquefies gelatin slowly ; grows at 

 room temperature, on ordinary culture-media, forming a 

 rose-red pigment on agar and potato. This micrococcus is 

 remarkable in being actively motile ; it possesses a flagellum. 

 It is stained by Gram's method. 



Micrococcus urese. Found in decomposed, ammoniacal 

 urine and in the air ; coccus .8 to I [* in diameter, occurring 



" Bakteriologische Diagnostik," 1891. 



" Manual of Bacteriology," 1893. 

 '"Die Mikro organism en" 1896. 

 1 " System der Bakterien," 1900. 

 5 " Manual of Determinative Bacteriology," 1901. 



