110 STUDIES IN IMMUNITY. 



it is usually more distinct and more deeply colored in those cocci 

 generated in the exudate. 



Leucocytes soon appear in the peritoneum following injection 

 of the streptococci. After an hour or two there are present some 

 mononuclears and many polynuclears. But these leucocytes 

 take up only a relatively small number of the bacteria injected, 

 which develop unrestrictedly and soon become very numerous. 

 Although the influx of the leucocytes is considerable they never 

 become sufficient to give a purulent appearance to the exudate 

 even several hours after inoculation. As soon as bacteria become 

 very numerous the leucocytes do not sensibly increase in number. 

 At this stage death is not very far distant. A rabbit that has 

 received 0.1 of a cubic centimeter of a culture into the peritoneal 

 cavity usually dies in 8 or 10 hours, rarely as late as 12 hours. The 

 greatest number of leucocytes, as a rule, are present 4 to 6 hours 

 after injection. 



A short time before death the exudate changes remarkably in 

 appearance. Two hours before death it is only slightly cloudy. 

 At death the exudate is reddish in color and composed of serum 

 which contains a rather large number of scattered red blood cells. 

 In this fluid leucocytes are still present and they are frequently 

 intact in appearance, but often degenerated and with no distant 

 protoplasmic outlines. The leucocytes, which were previously 

 abundant, are usually found collected in masses on the walls of 

 the peritoneum, particularly about the mesentery. The exudate 

 changes, then, in composition toward the end and becomes a harm- 

 ful medium for leucocytes and red blood cells. 



Two hours before death, when the exudate is no longer turbid, the 

 leucocytes present in the fluid which refuse to take up the strepto- 

 coccus will still take up other organisms (for example, the diphtheria 

 bacillus). Phagocytosis, however, under these conditions is never 

 so energetic as under similar conditions in the guinea-pig. In 

 general, it may be said that the exudate in streptococcus peritonitis 

 in the guinea-pig is always richer in leucocytes than it is in the 

 rabbit. 



A generalized infection, that is, an invasion of the blood by the 

 streptococci, occurs soon after intraperitoneal inoculations in the 

 rabbit. As soon as the bacteria in the exudate become very 



