OBTAINING NATURAL AGGRESSINS 



37 



A small incision is made in one of the intercostal spaces on the side 

 of the chest, and through this wound a long canula is introduced into the 

 pleural cavity. The animal as a rule rapidly succumbs to the infec- 

 tion. On autopsy, the pleural cavity is found to contain an exudate of 

 a reddish-brown color (hemorrhagic) on the side where the inoculation 

 was given, and of yellow serous fluid on the other side. The bloody exu- 

 date, about 15 c.cm., is removed with a sterile pipette, placed in a sterile 

 centrifuge tube to which is added 1.5 c.cm. of 5 per cent, carbolic acid 

 drop by drop (making the entire solution a 1-2 per cent, carbolic acid 

 dilution), agitated continually in- order to prevent precipitation, and 

 followed by centrifugalization at a high speed for many hours until it 

 becomes very clear. The upper clear part which is now free of bacteria, 

 or very nearly so, is pipetted off and heated for three hours at 44 C. Its 

 sterility is then tested and if no growth appears after forty-eight hours, it 

 is considered sterile. 



First Fundamental Aggressin Test. 



(Its Power of Increasing Severity of Infections.) 



