DIPLOCOCCUS PNEUMONIA 365 



Precipitins have been demonstrated in pneumococcus immune sera 

 by Neufeld,' Wadsworth,^ and others. Neufeld obtained precipitates 

 with pneumococcus cultures in which lysis had been produced by the 

 addition of bile. He found that normal rabbit's bile added to pneu- 



mococcus cultures (one drop to 1 c.c. of culture) caused the cultures to 

 become perfectly clear and transparent, and no longer contain demon- 

 strable pneumococcus cell bodies. The addition of pneumococcus im- 

 mune sera to such cultures produced precipitates. Wadsworth ob- 



' Neufeld, Zeit. f. Hyg., xi, 1902. ^ Wadsworth, loc. cit. 



5 Hiss, Jour. Exp. Med., vii, 1905, p. 564. 



