BACTERIA IN PNEUMONIA. 187 



those isolated in sputum septicaemia. Mice, guinea-pigs, 

 and rabbits were susceptible to them. (In one of his cases 

 Fraenkel observed Friedla'nder's coccus.) Similar cocci 

 were observed by Talamon and others, but the most 

 extensive investigations on the whole question were those of 

 \Veichselbaum, published in 1886. This author examined 

 129 cases of the disease, and included in this survey not 

 only acute croupous pneumonia, but lobular, hypostatic, 

 and septic pneumonias. From them he isolated four 

 groups of organisms, (i) Diplococcus pneumonia. This 

 he described as an oval or lancet-formed coccus, occurring 

 in pairs or in straight chains containing four to eight 

 individuals. It corresponded in appearance and growth 

 characters to Fraenkel's coccus. (2) Streptococcus pneu- 

 monia. This was less common than the last, was rounder, 

 and formed longer and more twisted chains, but on the 

 whole presented similar characters. It was more vigorous 

 in its growth, and could grow below 20 C, though it 

 preferred a temperature of 37 C. (3) Staphylococcus pyo- 

 genes aureus. (4) Bacillus pneumonia. This was a short 

 rod -shaped organism which must be classed among the 

 bacilli. Weichselbaum, however, was of opinion that it was 

 identical with Friedla'nder's pneumococcus. 



Of these organisms the diplococcus pneumoniae was by 

 far the most frequent, being observed in 94 cases of the 

 129 examined, and isolated by cultures in 54. It also 

 occurred in all forms of pneumonia. Next in frequency 

 was the streptococcus pneumonias, and lastly the bacillus 

 pneumoniae. Inoculation experiments were also performed 

 by Weichselbaum with each of the three characteristic cocci 

 he isolated. The diplococcus pneumoniae and the strepto- 

 coccus pneumoniae 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. : 



i. FraenkeVs pneumococcus, which is recognised to be 



