258 BACILLI PATHOGENIC IN MAN. 



bacilli. If fluids containing the cultures were injected 

 through the wall of the thorax into one lung of & 

 rabbit by means of a Pravaz syringe, no disease occurred, 

 rabbits being completely refractory to the organisms. 

 On the other hand, 32 mice treated in the same way 

 died ; on post-mortem examination reddish, turbid fluid 

 was found in both pleural cavities, both lungs were very 

 markedly reddened, almost completely devoid of air, and 

 showed scattered and ill-defined patches of red infiltra- 

 tion. Of 11 guinea-pigs, 6 showed similar appearances; 

 of 5 dogs, 1. If the cultivation was exposed to a 

 temperature of about 80 C. for 15 to 20 minutes, and then 

 injected into mice, the animals remained healthy, with 

 the exception of a few, where the injury was uninten- 

 tionally more severe. (This is a control experiment, 

 which in view of the serious injury done by such injec- 

 tions into the lungs of mice was absolutely necessary, 

 and still requires further repetition). Five mice were 

 also successfully infected by inhalation of cultivations, 

 and these, in like manner, presented typical appearances 

 of pneumonia. The same organisms could be cultivated 

 from the affected lungs of the animals experimented on* 

 Significance of In judging of the significance of Friedlander's pneu- 

 mom ' a bacilli, more especially for the purpose of clinical 



etiology of diagnosis, it is very important to note that they cannot 

 be distinguished with certainty from a number of other 

 organisms, either by their microscopical characters, or by 

 their cultivations. The same morphological characters 

 even the capsules are present in a number of bacteria ; 

 the character of the cultivations is extremely common,. 

 and shared by many species of bacteria; both the morpho- 

 logical and cultural characteristics were combined in 

 bacilli studied by Passet, Kreibohm, and others. Hence- 

 a definite diagnosis of these organisms is only possible- 

 by experiments on animals; and even in this respect 

 the distinction is difficult, because other organisms also- 

 show similar pathogenic action to that of Friedlander's 

 bacilli (for example, the bacillus isolated by Schou). 

 The allied pathogenic bacteria which have been as yet 

 isolated in a. similar manner show, however, differences 



