266 - SPECIFIC MICRO-ORGANISMS 



distinguished microscopically from the meningococcus or gono- 

 coccus. In examining material from the air passages this organ- 

 ism has to be considered. It is readily distinguished by cultural 

 methods. On ascitic-fluid agar the colony is dry and brittle, 

 quite dififerent from the meningococcus or gonococcus. Further- 

 more, it grows readily at once on ordinary agar., 



Diplococcus Pnexunoniae.- — Sternberg in 1880 injected the 

 saUva of healthy persons into rabbits and produced a rapidly 

 fatal bacteremia with abundant lance-shaped diplococci in the 

 blood and internal organs of the animal. Pasteur, independently 

 and at about the same time, injected the saliva of a boy suffering 

 from rabies into rabbits with a similar result. The organism 

 was spoken of as the diplococcus of sputum septicemia or the 

 septicemic microbe of saliva. Koch in 1881 demonstrated the 

 organism microscopically in sections of lung. Friedlaender 

 (1882-1884) found the organism microscopically. in ai large number 

 of cases of pneumonia and accurately described its form, the 

 capsules and staining properties. His cultures, however, which 

 were made on gelatin at room temperature, brought to develop- 

 ment not the pneumococcus but a wholly different organism which 

 he believed to be identical with it, Friedlaender's pneumobacillus. 

 A. Fraenkel obtained the first undoubted pure cultures on solidified 

 blood serum, proved the identity of the organism in pneumonia 

 with that of normal saliva seen by Sternberg and Pasteur, and 

 distinguished it absolutely from the pneumobacillus of Fried- 

 laender. He also succeeded in producing typical pneumonia by 

 injecting cultures of moderate virulence intravenously into rabbits. 



The pneumococcus is somewhat variable in form. In the 



animal body it occurs. in pairs of lance-shaped individuals with the 



points directed away from 'each other, and the pair is surrounded 



by a thick gelatinous capsule.^ The organism is always Gram- 



' In demonstrating the capsules, the method of Hiss gives excellent results. 

 Spread some blood or tissue juice on a cover-glass and as soon as the film of moisture 

 has disappeared, fix the preparation by heat. Then stain with hot aqueous gentian 

 violet and wash off the dye with a 20, per cent solution of copper sulphate. Examine 

 in the copper solution, Blot the preparation, dry it in air and mount in balsam. 



