HISTORY OF PNEUMOCOCCUS: 1875-1890 7 



sidered them not as a passive precipitate, but as a product of the 

 vital action of the coccus. Applying several microchemical tests to 

 the capsular material, he felt justified in concluding that it con- 

 sisted of mucin or an allied substance. When one remembers that 

 mucin is a protein-carbohydrate complex in which the saccharide 

 yields on hydrolysis two glucosamin, one acetic acid, and two 

 hexose molecules, one appreciates the value of this observation in 

 anticipating the discovery of the soluble specific substance or cap- 

 sular polysaccharide by Heidelberger and Avery. Friedlander cul- 

 tivated these organisms on Koch's coagulated blood serum, upon 

 which they grew as round and elliptical cocci. His descriptions of 

 the colonies on this medium corresponded with the appearance of 

 the colonies of typical pneumococci. He also said that he had car- 

 ried the cultures through eight transfers in meat-infusion peptone 

 gelatin. In this medium the coccus lost its capsule and grew in 

 "nail-form" colonies. 



When one-half to one cubic centimeter of aqueous suspensions of 

 the gelatin cultures was injected into the lungs of rabbits no in- 

 fection resulted. Guinea pigs inoculated in this way were more sus- 

 ceptible, six of nine becoming infected. Mice were far more sus- 

 ceptible, all dying of infection. From the pleural and lung exudate 

 of the infected animals Friedlander isolated typical diplococci. In 

 four of twelve mice he succeeded in producing infection by inhala- 

 tion. One of four dogs succumbed to the injection of cultures into 

 the lung, and this animal at necropsy showed red and gray hepa- 

 tization of the lung. From these areas, from the blood, and from 

 the right pleural cavity, Friedlander recovered typical organisms. 

 He noted variations in the capsule of the organisms depending 

 upon their propagation in mice, guinea pigs, dogs, and man. 



At that time, Friedlander was unable to demonstrate cocci in the 

 blood of pneumonia patients, but in 1884 489 " 90 reported that he 

 had cultivated typical micrococci from the blood of one of six pa- 

 tients. The cocci were encapsulated and virulent for mice, but by 

 the method tested were avirulent for rabbits. It was in his first 



