226 THE ACUTE PNEUMONIAS 



with those isolated in sputum septicaemia. The most extensive investi- 

 gations on the whole question were those of Weichselbaum, published 

 in 1886. This author examined 129 cases of the disease, including 

 cases not only of acute croupous pneumonia, but of lobular and septic 

 pneumonia. From them he isolated four groups of organisms. (1) 

 Diplococcus pneumonia;. This he described as an oval or lancet-formed 

 coccus, corresponding in appearance and growth characters to Fraenkel's 

 coccus. (2) Streptococcus pneumonia?. This on the whole presented 

 similar characters to the last, but it was more vigorous in its growth, 

 and could grow below 20 C. , though it preferred a temperature of 37 C. 

 (3) Staphylococcus pyogenes aureus. (4) Bacillus pneumonice. This was 

 a rod-shaped organism, and was identical with Friedlander's pneumo- 

 coccus. Of these organisms the diplococcus pneumoniae was by far the 

 most frequent. It also occurred in all forms of pneumonia. Next in 

 frequency was the streptococcus pneumonias, and lastly the bacillus 

 pneumonias. Inoculation experiments were also performed by Weichsel- 

 baum with each of the three characteristic cocci he isolated. The 

 diplococcus pneumonias and the streptococcus pneumonias both gave 

 pathogenic effects of a similar kind in certain animals. 



The general result of these earlier observations was to establish 

 the occurrence in connection with pneumonia of two species of 

 organisms, each having its distinctive characters, viz. : 



1. Fraenkel's pneumococcus^ which is recognised to be identical 

 with the coccus of " sputum septicremia," with Weichselbaum's 

 diplococcus pneumonias, and with his streptococcus pneumonias. 



2. Friedlander's pneumococcus (now known as Friedlander's 

 pneumobacillus), which is almost certainly the bacillus pneu- 

 moniae of Weichselbaum. 



We shall use the terms " Fraenkel's pneumococcus " and 

 "Friedlander's pneumobacillus," as these are now usually 

 applied to the two organisms. 



Microscopic Characters of the Bacteria of Pneumonia. 

 Methods. The organisms present in acute pneumonia can best 

 be examined in film preparations made from pneumonic lung 

 (preferably from a part in a stage of acute congestion or early 

 hepatisation), or from the gelatinous parts of pneumonic sputum 

 (here again preferably when such sputum is either rusty or 

 occurs early in the disease), or in sections of pneumonic lung. 

 Such preparations may be stained by any of the ordinary weak 

 stains, such as a watery solution of methylene-blue, but Gram's 

 method is to be preferred, with Bismarck-brown or Ziehl-Neelsen 

 carbol-f uchsin (one part to ten of water) as a contrast stain ; 

 with the latter it is best either to stain for only a few seconds, 

 or to overstain and then decolorise with alcohol till the ground 

 of the preparation is just tinted. The capsules can also be 

 stained by the methods already described (p. 109). In such 

 preparations as the above, and even in specimens taken from 



