366 PATHOGENIC MICROORGANISMS 



tanned similar precipitates with pneumococcus cultures treated with 

 concentrated salt solution as described above (see p. 363). 



Pneumococcus immune sera also contain specific phagocytosis- 

 stimulating substances. The first investigators to describe these sub- 

 stances for pneumococcus sera, Neufeld and Rimpau,' separated them 

 from the opsonins on the basis of their greater thermo-stability and 

 named them bacteriotropins. It is doubtful whether such differentia- 

 tion is tenable. Great importance for pneumococcus immunity is 

 attributed to these bodies by some authors. This question has been 

 studied more recently by Park and Williams,^ however, who were un- 

 able to find distinct parallelism between opsonic power and the protec- 

 tive value of a serum. 



Passive immunization with pneumococcus immune sera has been 

 extensively attempted. Washburn,' Mennes,* Pane,^ and many others 

 have succeeded in protecting subsequently infected animals by treatment 

 with such sera. Neufeld and Haendel in Germany, and in this 

 country Cole, have recently used pneumococcus immune sera exten- 

 sively in the treatment of man. The serum, given intravenously, 

 seems to exert a favorable influence, and while unfinished, the work 

 is exceedingly encouraging. Encouraging results were obtained by 

 Hiss in treatment of pneumococcus infection in animals and by Hiss 

 and Zinsser * in treatment of pneumonia in man with aqueous leuco- 

 cyte extracts. 



Experiments both with passive immunization and with agglutina- 

 tion show that all pneumococci do not react alike. Sera which will 

 protect white mice against the homologous strain react similarly 

 to some other strains, but not to all. Neufeld and Haendel ' as a result 

 of protection experiments concluded that the majority of pneumococci 

 belonged to one type, but that a number of other types could be recog- 

 nized. On the basis of agglutination and protection tests Dochez and 

 Gillespie * describe three distinct races of pneumococci and a fourth 

 group of heterogeneous strains. One of these definite types occurred 

 in nearly half of their sixty-two cases of lobar pneumonia. 



1 Neufeld und Rimpau, Deut. med. Woch., 1904. 



' Park and Williams, Jour. Exp. Med., vii, 1905. 



3 Washburn, Brit. Med. Jour., 1897. 



• Mennes, Zeit. f. Hyg., 1897. 



' Pane, Rif. med., 1897. 



" Hiss and Zinsser, Jour. Med. Res., xix, 1908. 



' Neufeld and Haendel, Arb. aus dem Kais. Gesunds., 1910, xxxiv, 293. 



» Dochez and Gillespie, J, A. M. A., 1913, Ixi, 727. 



