1 68 SUPPURATION AND ALLIED CONDITIONS. 



cultures in gelatine often being alive after having been kept 

 for several months. It also requires a rather higher 

 temperature to kill it than most spore -free bacteria, viz. 

 80 C. for half an hour (Lubbert). 



The Staphylococcus pyogenes albus is similar in char- 

 acter 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 is less virulent than 

 the other two. 



The Staphylococcus cereus albus and Staphylococcus ceretis 

 flavus are of much less importance. They produce a 



wax -like growth on 

 gelatine without lique- 

 faction, hence their 

 name. 



Streptococcus pyo- 

 genes. This organism 

 is a coccus of slightly 

 larger size than the 

 Staphylococcus aureus, 

 . ** about i /A in diameter, 



""""^^ J 1 ^ /^, and forms chains which 



may contain a large 



/, yX^'^f number of members, 



especially when it is 

 growing in fluids (Fig. 

 47). The chains vary 

 somewhat in length in 

 different specimens of 

 the streptococcus, and on this ground varieties have been 

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



FIG. 47. Streptococcus pyogenes, young 

 culture on agar, showing chains of cocci. 

 Stained with weak carbol-luchsin. x 1000. 



