184 SUPPURATION. 



will develop. The presence of the germ under normal con- 

 ditions would also account for those isolated cases of pneu- 

 monia occurring in individuals who have not been exposed 

 to infection, and who have not come in contact with a case 

 of pneumonia. The possibility of contracting the disease 

 has been present all the time and under favorable conditions 

 the germ has become active. A few instances of transmission 

 from the mother to the foetus through the placenta have been 

 recorded. 



Immunity : It is believed by most investigators that immu- 

 nity after an attack of pneumonia is present in a very slight 

 degree and is of only short duration, or that it never exists. 

 The brothers Klemperer isolated a substance from the serum 

 of immunized rabbits which protected animals inoculated with 

 the pneumococcus. They called this substance pneumoprotein. 

 Washburne also prepared an antipneumococcus serum by in- 

 oculating a horse with virulent pneumococci. It appeared to 

 be superior to the serum of the Klemperers inasmuch as it 

 exerted a protective action in the human being as well as in 

 animals. This question of immunization against the pneumo- 

 coccus is still largely a matter of conjecture ; but further 

 investigation will undoubtedly place the antipneumococcus 

 serum on a firmer foundation, at least so far as the pre- 

 vention of the disease is concerned. 



The use of the serum for therapeutic purposes has been 

 attended with good results in the hands of a few clinicians; 

 although in the great majority of instances the injection of 

 even a large amount of serum does not appear to have 

 altered the course of the disease in any way. The dyspnoea 

 was lessened, but no other change was noted. It is perfectly 

 harmless even in large doses, so that its use is not attended 

 with danger. Another author, in an experience with 106 

 cases of lobar pneumonia, found that it lowered the tempera- 

 ture, relieved the pain, ameliorated all the symptoms, and 

 hastened the crisis. The number of cases in which the 

 serum has been used for therapeutic purposes is so small, 

 however, that it is impossible to express any opinion as to its 

 value either as a curative or preventive agent. 



