410 BIOLOGY OF PNEUMOCOCCUS 



pneumococcic horse serum a close correlation between protection, 

 precipitin, and agglutination titer for Type I Pneumococcus.* 

 Similarly, Barnes, Clarke, and Wight (1936), 82 using a modified 

 precipitin test, found that the correlation between precipitin and 

 protective antibody content was sufficiently close to warrant the 

 substitution of the precipitin test for the animal test in titration 

 of the protective value of antipneumococcic serum.* 



ADDITIONAL DATA 



Kyes (1911) 765 employed domestic fowls for the preparation of 

 antipneumococcic serum, giving the birds repeated inoculations of 

 large doses of virulent pneumococci. Kyes concluded that by this 

 method it was possible to obtain serum possessing distinct protec- 

 tive action against pneumococci within certain hosts. In 1920, 

 Wadsworth, 1460 after injecting a single dose of standardized pneu- 

 mococcal vaccines of Types I, II, and III into mice, found that it 

 was possible with Type I vaccine to produce protection against 

 Type I cultures but not against Type II or III strains. In the case 

 of Type II vaccine there appeared to be protection exclusively 

 against the homologous organism while, when Type III vaccine 

 was administered, there was no protection against any of the three 

 types. Cecil and Blake, 206 after injecting monkeys with saline sus- 

 pensions of heat-killed virulent Type I pneumococci, could demon- 

 strate protective antibodies in the serum although the animals 

 eventually succumbed to intratracheal inoculation with the same 

 living strains. Later, Cecil with Steffen, 213 by the intravenous and 

 subcutaneous injection of larger doses of pneumococcal vaccine, 

 succeeded in completely protecting monkeys against infection and 

 made the seemingly paradoxical observation that protective sub- 

 stances might or might not be present in the serum of the immune 

 monkeys. 



The same authors 214 reported (1925) a similar condition in 

 monkeys immunized by intratracheal vaccination, and decided that 



* See page 378 of this chapter. 



