STREPTOCOCCUS PYOGENES. 149 



for several months. It also requires a rather higher tempera- 

 ture to kill it than most spore-free bacteria, viz. 80 C. for 

 half an hour (Liibbert). 



The Staphylococcus pyogenes albus is similar in character 

 with the exception that its growth on all the media is white. 

 The colour of the Staphylococcus aureus may become less 

 distinctly yellow after being kept for some time in culture, 

 but it never assumes the white colour of the Staphylococcus 

 albus, and it has been found impossible to transform the 

 one organism into the other. . Both organisms are common 

 in air, dust, and especially on the surface of the skin. The 

 Staphylococcus pyogenes citreus which is less frequently 

 met with, differs in the colour of the cultures being a 

 lemon yellow, and it is stated to be less virulent than the 

 other two. 



The Staphylococcus cereus albus and Staphylococcus cereus 

 flarus are of much less importance. They produce a 

 wax - like growth on ''"'mi 



gelatine without lique- 

 faction, hence their 

 name. 



Streptococcus pyo- 

 genes. This organism 

 is a coccus of rather 

 larger size than the . 

 Staphylococcus aureus, v 

 about i /z in diameter, 

 and forms chains which 

 may contain a large 

 number of members, 

 especially when it is X"*"*" 



growing in fluids (Fig. 

 A i\ The chains vqrv FlG ' 42. Streptococcus pyogenes, young 



15 Fa y culture on agar, showing chains of cocci, 

 somewhat in length in Stained with weak carbol-fuchsin. x 1000. 



different specimens of 



the streptococcus, and on this ground varieties have been 

 distinguished, e.g., the streptococcus brevis and strepto- 

 coccus longus (vide infra). As division may take 



h* 



\* 



