1 6 QUATERCENTENARY STUDIES IN PATHOLOGY 



The high opsonic index registered in cases of closed empyaemata may 

 be regarded as an expression of immunisation from resorption of 

 immunising products from the pleural cavity. When opened, and the 

 conditions favouring resorption removed, the opsonin in the serum is 

 restored to normal in a shorter or longer period. 



That the variation in opsonin in acute croupous pneumonia is a 

 specific variation for the pneumococcus is shown by testing the opsonic 

 content of the blood for another bacterium — e.g,^ the staphylococcus. 

 Thus it is shown that while the pneumococcal opsonin undergoes great 

 changes in quantity during the course of acute croupous pneumonia, 

 the opsonic content for staphylococcus varies from the normal in only a 

 slight extent. Several of the cases were tested throughout, and in each 

 case this was verified. Thus, one day three patients gave indices for 

 pneumococcus of 0'5, 0*65, and 0*95, and staphylococcus 1*09, 0*85, and 

 i*o respectively. Two days later, the same cases were tested for both 

 organisms, giving indices of 0*85, 1*3, and 1*03 respectively, while the 

 staphylococcic indices were i*o, 0'86, and I'oi respectively. 



Another method of demonstrating the specificity of opsonin in the 

 serum is by an absorption experiment. Serum is taken and the mixture 

 digested with a measured quantity of thick pneumococcal emulsion in. 

 normal salt solution for fifteen minutes at 37° C. A similar measured 

 quantity of normal saline solution is added to the control. The cocci 

 are then removed by centrifugalisation and the supernatant fluid tested 

 against the control. The result is: Control for pneumococcus, I'oo; 

 supernatant for pneumococcus, 0*12; control for staphylococcus, i*oo; 

 supernatant fluid for staphylococcus, 0*95. The remainder of the 

 supernatant fluid is divided into two equal parts, and a quantity of thick 

 staphylococcus emulsion added to one while an equal quantity of saline 

 is added to the other half Both are digested for fifteen minutes at 37° 

 C. The cocci are deposited by the centrifuge. The supernatant fluid is 

 tested with pneumococcus, stahpylococcus, and tubercle bacillus. 



For Pn. For Staph. For T. B. 

 Opsonic content of control . . i i i 



II II supernatant fluid o'lo 0*13 076 



From these experiments it may be deduced that there is an opsonin 

 specific for each organism or group of organisms (the opsonin for 

 Staphylococcus aureus does not seem to be different from that of Staphylo- 



(380) 



