ANTIBODIES TO PNEUMOCOCCUS 369 



during the period of active infection. With the recovery of the 

 animal the reactivity of the serum disappears almost as abruptly 

 as it appears with the onset of the disease. Abernethy reports that 

 the study demonstrates: 



. . . the variable response of two different hosts to the same bacterial 

 agent. In one species, the monkey, pneumococcus infection was accom- 

 panied by the demonstration of certain changes in the serum during the 

 acute period of illness. In the other, the rabbit, these changes were not 

 observed. These observations suggest that during infection in the mon- 

 key either some newly formed substance or some alteration occurs in the 

 serum which renders it inactive in precipitation tests with this particu- 

 lar polysaccharide derived from Pneumococcus. Assuming this to be the 

 case, then the failure to demonstrate the phenomenon in the rabbit 

 might be explained either by the absence of or qualitative differences in 

 the serum during infection. 



The phenomenon of precipitation of the somatic or C polysac- 

 charide of Pneumococcus cannot be explained on the basis of any 

 of our present orthodox conceptions of immunity. The property 

 is not limited to the serum of individuals ill with pneumococcal in- 

 fection, since it is also possessed by the serum of patients suffering 

 from rheumatic fever, bacterial endocarditis, and lung abscess, 

 but not from other febrile diseases. 



Furthermore, unlike other specific antibodies, the substance ca- 

 pable of precipitating the C Fraction appears in the serum of the 

 pneumonia patient within the first twenty-four hours of the dis- 

 ease, and — again unlike any antibodies that we know — disappears 

 from the serum with the beginning of recovery. Because of their 

 importance in the body's defense against pneumococcal and other 

 infections, the discovery of the chemical identity of the precipitat- 

 ing substance in the serum of pneumonia patients and of the chemi- 

 cal or physical processes involved in the particulation of the so- 

 matic polysaccharide is awaited with keen interest. 



Jungeblut believed that lipoid substances extracted from Pneu- 

 mococcus were responsible for the reaction but, as the author 

 pointed out, the method of preparing the alcohol-soluble antigen 



