164 STAPHYLOCOCCIC INFECTION 



in a few hours. After death the pleural exudate in this animal is 

 found to be sterile. Therefore, the animal does not die from infection 

 but from intoxication. Bail's explanation is that the exudate is bac- 

 tericidal and in the second animal quickly splits up the cocci with the 

 liberation of enough poison to kill it. This seems not only rational, 

 but the most probable explanation. 



In most of the suppttrative affections of man either the strepto- 

 coccus or the staphylococcus, or both, play some part, either as primary 

 or secondary cause. Other bacteria may be present, but these are the 

 most essential. It is true that there may be an aseptic suppuration 

 and it is also true that other bacteria may incite suppurative processes, 

 but these are rare exceptions. Among the cutaneous and subcutaneous 

 lesions which may be due, either wholly or in part, to the staphylo- 

 coccus, we may mention acne, erysipelas, impetigo, lymphangitis, boils, 

 abscesses, phlegmons and pemphigus. In the alimentary canal this 

 organism may infect any part from the beginning to the end. Rarely 

 it closely simulates diphtheria in the formation of membrane, and the 

 osseous system seems to furnish favorable conditions for its growth. 

 Abscesses in various parts of the body are most frequently due to this 

 organism alone or in company with the streptococcus. Among our 

 domestic animals it causes the same or similar lesions. 



While it is true that the serum of an animal highly immunized to 

 the staphylococcus agglutinates this organism in fairly high dilutions, 

 serodiagnosis of staphylococcic infection has not proved of great value. 

 Fortunately, it is rarely needed. 



The contest between the phagocytes and the pus germs is waged on 

 fairly even terms. Each secretes an agent which is destructive to the 

 other. The cocci prepare and use the leukocidin, and the phagocytes 

 employ a bactericidal ferment. The contestants are wary in approach 

 and frequently retreat. When the cocci are only slightly virulent 

 and form but little or no leukocidin, the phagocytes are bold and 

 rapidly devour their enemies. In this case, we say that the chemotaxis 

 is positive. But when the cocci are highly virulent and pour out large 

 amounts of leukocidin, the phagocytes approach with greater caution 

 or retreat. Then, we say that the chemotaxis is negative. Phagocytes 

 feed voraciously on unarmed cocci, but when the latter are prepared, 

 the former seem less hungry. The leukocidin is best prepared for study 



