280 PATHOGENIC BACTERIA. 



to Weichselbaum, 1 however, that we are indebted for the 

 discovery of the relation which the organism bears to 

 pneumonia. 



The organism (Fig. 60) is variable in its morphology. 

 When grown in bouillon it is oval, has a pronounced dis- 

 position to occur in pairs, and not infrequently forms 

 chains of five or six members, so that some have been 

 disposed to look upon it as a streptococcus (Gamaleia). 

 In the fibrinous exudate from croupous pneumonia, in 



Fig. 60. — Diplococcus pneumoniae, from the heart's blood of a rabbit; x 1000 

 (Frankel and Pfeiffer). 



the rusty sputum, and in the blood of rabbits and mice 

 containing them the organisms are arranged in pairs, 

 exhibit a distinct lanceolate shape, the pointed ends 

 generally approximated, and are usually surrounded by 

 a distinct halo or capsule of clear, colorless, homogeneous 

 material, thought by some to be a swollen cell-wall, by 

 others a mucus-like secretion given off by the cells. When 



1 Wiener vied. Jahrbuch, 1886, p. 483. 



