THE PNEUMOCOCCU8 AND PNEUMONIA 439 



logical facts had been ascertained. This idea, so well founded upon 

 the nature of the clinical course of the disease, with its violent onset 

 and equally rapid defervescence, led many of the earlier bacteriol- 

 ogists to make it the subject of their investigations a subject made 

 doubly difficult by the abundant bacterial flora found normally in 

 the upper respiratory passages, and by the fact, which is now recog- 

 nized, that lobar and other pneumonias are by no means always 

 caused by one and the some microorganisms. 



Cocci of various descriptions and cultural characteristics were 

 isolated from penumonia cases by Klebs, 5 Koch, fi Giinther, 7 Talamon, 8 

 and many others, which, however, owing to the insufficient differen- 

 tial methods at the command of these investigators, cannot positively 

 be identified with the microorganism now known to us as Diplo- 

 coccus pneumoniae or the pneumococcus. Although thus unsuccessful 

 as to their initial object, these early investigations were by no means 

 futile, in that they gave valuable information regarding the manifold 

 bacterial factors involved in acute pulmonary disease and inci- 

 dentally led to the discovery by Friedlander 9 of B. mucosus 

 capsulatus. 



A tabulation is given in the monograph published on acute lobar 

 pneumonia by Avery, Chickering, Cole and Dochez. 10 " Among 529 

 cases diagnosed from the clinical and pathologic features as acute 

 lobar pneumonia, the following were the etiologic agents concerned: 



Diplococcus pneumoniae 454 



Friedlander 's bacillus 3 



Bacillus influenzae 6 



Streptococcus pyogenes 7 



Streptococcus mucosus 1 



Staphylococcus aureus 3 



Cases of mixed infection with combinations of Staphylococcus aureus, Fried- 

 lander 's bacillus, B. influenzae, Streptococcus pyogenes, and Strepto- 

 coccus viridans 6 



Undetermined (Most of them occurring before accurate methods for de- 

 termining the etiologic agent had been devised 49 



Total 529 



5 Klebs, Arch, f . exp. Path., 1873. 



6 Koch, Mitt. a. d. kais, Gesundheitsamt, Bd. 1. 



7 Giinther, Deut. mod. Woch., 1882. 



8 Talamon, Progr. med., 1883. 



9 Friedlander, Virchow's Arch., Ixxxvii. 



10 Avery, Chickering, Cole and Dochez, Monograph of The Rockefellei Inst. for 

 Med. Res., No. 7, Oct. 16, 1917. 



