242 BIOLOGY OF PNEUMOCOCCUS 



filter, and precipitated with acetic acid in the cold. After separa- 

 tion of the precipitate (phosphoprotein or nucleoprotein), acid 

 was added until no more precipitate came out of solution when the 

 precipitate was discarded. After filtration, the solution was acidi- 

 fied and boiled for three to five minutes, then again filtered and 

 neutralized. The filtrate was the residue solution. It became turbid 

 on the addition of ten volumes of alcohol, and the precipitate con- 

 tained the antigenic substance, although the authors suggested 

 that it might have been mechanically thrown down. 



The residue gave a specific precipitate with homologous anti- 

 serum but no complement fixation with equine antipneumococcic 

 serum, nor did it stimulate any immune-body production in ani- 

 mals injected with it. The substance, however, excited a positive 

 reaction when injected intradermally into normal guinea pigs and, 

 to a lesser degree, in tuberculous pigs. Its resistance to autoclav- 

 ing and to boiling in alkaline solutions would seem to establish a 

 close relationship to the soluble specific substance described by 

 Dochez and Avery. 



Two years later, Zinsser with Tamiya 1584 extended the study of 

 pneumococcal residue and pneumococcal protein. Some rabbits 

 were immunized with agar-grown pneumococci washed with 2 per 

 cent formalin in saline solution, and other rabbits with Berkefeld 

 filtrates of pneumococci dissolved in minimal amounts of bile. The 

 serum from these animals was then tested for precipitins against 

 the two antigens. In the discussion of the experimental results Zins- 

 ser and Tamiya expressed the opinion that the antigens consisted 

 of two substances : the one obtained by treating pneumococci with 

 weak alkali, the other by f ractioning the extract by acid precipita- 

 tion. The one was a nucleoprotein independently antigenic, induc- 

 ing antibodies which reacted only with itself and not with the resi- 

 due ; the other was the residue material incapable of inducing any 

 kind of antibody response but capable of reacting with antibodies 

 formed by the injection of the whole bacteria. The two substances, 

 therefore, although in a crude state, corresponded in their immu- 



