COVER-SLIPS AND SECTIONS. 275 



which serve to protect rabbits from twice the fatal dose 

 of a staphylococcus culture. Similarly the serum of 

 immunized rabbits and goats, as shown by the exper- 

 iments of Petersen, possesses about the same degree of 

 protective powers. No antitoxic power could be dem- 

 onstrated in the serum of the treated animals. The 

 extremely limited degree of the protective power of 

 antistaphylococcus serums makes them useless for cura- 

 tive purposes in human beings, as Petersen calculated 

 that an adult would require from 350 to 700 c.c. of the 

 serum at a single dose, as judged by its effects on the 

 lower animals. 



OTHER COMMON PYOGENIC ORGANISMS. 



MICROCOCCUS PYOGENES (Rosenbach), Migula, 1900. Synonyms: 

 Staphylococcus pyogenes albus, Rosenbach, 1884 ; Micrococcus pyo- 

 genes albus, Lehmann and Neumann, 1896. 



MICROCOCCUS CITREUS (Passet), Migula, 1900. Synonym : Staphy- 

 lococcus pyogenes cltreus, Passet, 1895. 



The pus of an acute abscess in the human being 

 may sometimes contain organisms other than micro- 

 coccus aureus. Micrococcus pyogenes and citreus may be 

 found. The colonies of the former are white, those of 

 the latter are lemon color. With these exceptions they 

 are in all essential cultural peculiarities similar to micro- 

 coccus aureus. As a rule, they are not virulent for 

 animals, and when they do possess pathogenic proper- 

 ties, it is in a much lower degree than is commonly the 

 case with the golden micrococcus. Streptococcus pyo- 

 genes is also sometimes present. The commonest of 

 the pyogenic organisms, however, is that just described, 

 viz : micrococcus aureus. An organism that is almost 

 universally present in the skin, and is often con- 

 cerned in producing mild forms of inflammation, is 



