GENUS MICROCOCCUS 211 



M. pyogenes growing on blood-agar plate cultures. Neisser 

 and Wechsberg found that the hemolytic substance could be 

 found in filtrates of bouillon culture. The quantity produced 

 varied to a large extent in different strains of the organism 

 and, it has been asserted, bears some relation to the virulence 

 of the particular organism. It is further stated that the cul- 

 ture medium most favorable for the formation of these sub- 

 stances is alkaline beef bouillon. The hemolysin is said by 

 some to be destroyed by heat at 56 C. and others claim that a 

 higher temperature is required. 



Micrococcus pyogenes variety albus (Rosenbach) and M. 

 pyogenes variety citreus (Passet) are practically identical with 

 M. pyogenes excepting in the color of the growth on solid 

 media. They do not appear, however, quite so frequently and 

 as a rule they do not seem to possess as uniform virulence as 

 M. pyogenes variety aureus. 



MICROCOCCUS CAPRINUS. 



Place in nature. This micrococcus was described by 

 Mohler and Washburn x in the organs of goats that had died 

 of the disease known as l * Takosis. ' ' 



Morphology. This organism is spherical or oval, with a 

 diameter of 0.8 to 1.0 /x when grown in bouillon cultures. It 

 frequently appears in pairs and in short chains with a diam- 

 eter transverse to the chain, longer than the longitudinal di- 

 ameter. It exhibits considerable variation in size. In older 

 cultures there is a greater tendency to form chains. They 

 exhibit quite pronounced Brow r nian movement. 



Staining. It stains indistinctly with Loeffler's methy- 

 lene blue and the standard aqueous aniline dyes, with the 

 exception of gentian violet. It stains readily with carbol- 

 fuchsin. 



Cultivation. It is an aerobe and facultative anaerobe. 

 It grows in both slightly alkaline and acid media. Its most 

 favorable temperature is about 35 C. 



1 Mohler and Washburn. Bulletin No. 45, B. A. I., U. S. Dept. 

 Agric., 1903. 



