PNEUMOCOCCAL VACCINES 491 



three days after the injection of a vaccine consisting of sterilized, 

 intact organisms of Types I and II, while similar immune effects 

 were demonstrable on the fourth day after the administration of 

 filtrates of broth cultures of the cocci. In an experimental way, 

 Goodner 626 ' 6 ' 62B showed that protective and other antibodies were 

 present in the blood of rabbits in one to two days after intrader- 

 mal inoculation with living pneumococci. In immunization tests 

 carried out on man with various antigenic preparations made from 

 Type I and Type II pneumococci, Felton, Sutliff, and Steele 434 

 found that antibodies appeared in the blood stream to a slight ex- 

 tent on the fourth or fifth day after injection and increased up to 

 a maximum on the fourteenth day. The literature contains many 

 references to the early development of humoral, immune substances 

 or of increased resistance engendered by the administration of 

 pneumococcal antigens, but it seems scarcely necessary to relate 

 them. 



The statement was made earlier in this chapter that the dura- 

 tion of the immune state established by the administration of pneu- 

 mococcal vaccines, as far as present evidence indicated, could not 

 be expected to surpass that arising during an attack of pneu- 

 monia. All the experiments in which this time element was noted 

 bear witness to the validity of the statement. Maynard, 872 basing 

 his observations on the incidence of natural immunity in vacci- 

 nated natives in the Rand as compared to that of unvaccinated na- 

 tives, reported that the protection conferred by the immunization 

 treatment appeared to be greatest immediately or shortly after 

 vaccination and then progressively diminished, until after a period 

 of about four months it was lost. In the rabbit, following the 

 intradermal injection of living pneumococci, Goodner could no 

 longer demonstrate the existence of active immunity after a lapse 

 of fifty to sixty days. Although the presence of demonstrable spe- 

 cific antibodies in the serum of a vaccinated individual may or may 

 not be an index of resistance to pneumococci, their appearance 

 and persistence bear witness to the fact that the physiological 



