STAPHYLOCOCCUS PYOGENES. 161 



one locality. With but few exceptions they are always para- 

 sitic. They are always found on the surface of the body, in 

 the mouth, nose, eyes, and ears, beneath the finger-nails, in 

 the saliva, and occasionally in the feces ; in the dust of the 

 street, on the floors and walls of houses and hospitals, and 

 wherever they may have been deposited from a previous 

 infection. Occasionally they are found in the air and in water. 

 Biology and morphology : The staphylococci are from 0.7 p 

 to 1.2 p. in diameter, and have an arrangement resembling a 

 bunch of grapes (staphylos), from which they derive their 

 name. The typical grouping is seen only in preparations 



FIG. 67. 



Staphylococcus pyogenes. (Park.) 



made directly from pus (Fig. 67). In culture specimens the 

 Staphylococcus occurs usually as a simple micrococcus, some- 

 times in masses, and sometimes as a typical Staphylococcus. 

 Staphylococci are not motile, and have no flagella. They 

 divide by fission. 



The entire group grows very readily on all the various 

 culture-media, and equally well in the presence or absence of 

 oxygen, but pigment is formed only in the presence of oxygen. 

 The temperature optimum is that of the body, 37 C. ; but 

 they exhibit some growth in a temperature as low as 6 C. 

 and as high as 44 C. They are stained readily with all the 

 anilin dyes, and also by Gram's method. 



11 Bact. 



