'I HE ORGANISMS OF SUPPURATION. ■■ I7S 



instance, if we take from an actively growing agar-agar 

 culture a small specimen for microscopic examination, 

 we always find a large number of diplococci, and even 

 short three-celled chains, that is to say the commence- 

 ment of streptococcus growth. True specific charac- 

 ters cannot be influenced by any methods of culture, 

 they should remain constant under all conditions. 



There are some other bacteria, which excite suppu- 

 ration, and which are very similar to the Stafhylo- 

 coccus pyogenes aureus, but which are distinguished 

 from it by the colour of their colonies. The most 

 important of these are the Staphylococcus pyogenes 

 citreus, and the Staphylococcus pyogenes alhus. The 

 former is somewhat rare, and, as a rule, only occurs 

 in acute abscesses. Its appearance in cultivations 

 exactly resembles that of the aureus, except for its 

 lemon-yellow colour; neither with the microscope, 

 can any striking difference be discovered between 

 them, only it appears as if in the citreus the cells 

 had less inclination to group themselves together, 

 and would rather remain isolated. The color- 

 ation of the colonies, however, is very distinctly 

 different from the golden or orange-yellow of the 

 Staphylococcus pyogenes aureus. The albus occurs 

 more frequently than the citreus, although less fre- 

 quently than the aureus ; sometimes it occurs alone, 

 sometimes in conjunction with the latter. Except 

 that the cultures, even when old, remain white, in 



