BACTERIA IN CROUPOUS PNEUMONIA. 293 



1885, and led me to the identification of the oval coccus found in this ma- 

 terial with the coccus found in my own saliva (by inoculations into rabbits) 

 in September, 1880, and subsequently studied by me in an extended series 

 of experiments made during the following years, 1880-84. 



But, at the same time, I fell into the error of inference, previously made 

 by Prof. See, by Salvioli, and others, and assumed that the "pneumo- 

 coccus " which Friedlander had obtained from the same source was the same, 

 although I found it difficult to reconcile the experimental data, inasmuch 

 as he had obtained uniformly negative results in his inoculations into 

 rabbits. To explain this discrepancy I suggested that Friedlander's pneu- 

 mococcus was probably a variety having a different degree of pathogenic 

 power. 



This supposition seemed to find support in the fact, which I had previ- 

 ously observed, that my Micrococcus Pasteuri became attenuated, as to its 

 pathogenic power, when the cultures were kept for some time; and that 

 there seemed, from the experimental evidence before me, to be different 

 pathogenic varieties in the buccal secretions of different individuals. At 

 this time I had not seen a culture of Friedlander's bacillus. Later, in the 

 autumn of 1885, when I made its acquaintance in Dr. Koch's laboratory, I 

 recognized my mistake and hastened to correct the error. 1 



For a detailed account of my experiments with pneumonic exudate I 

 must refer to my paper published in the ' ' Transactions of the Pathological 

 Society of Philadelphia" (vol. xii.) and in the American Journal of the 

 Medical Sciences (July, 1885). 



With reference to my conclusion that the oval coccus of Talamon and 

 of Salvioli was identical with my Micrococcus Pasteuri, I may say that 

 this conclusion has been sustained by the subsequent investigations of 

 Frankel, Weichsel baum, Bordoni-Uffreduzzi, Netter, Grameleia, and others. 



Frankel's first paper relating to the presence of this microorganism in 

 pneumonic exudate was published in 1885. 



Having ascertained that his own saliva contained this oval micrococcus, 

 he was induced to make an extended and interesting series of experiments 

 which led him to the conclusion that this microorganism is far more con- 

 stantly present in the exudate of fibrinous pneumonia than is the so-called 

 " pneumococcus " of Friedlander. He says: 



" Finally, as regards the relative frequency of the two hitherto investi- 

 gated microorganisms in cases of pneumonia, no positive statement can yet 

 be made. Nevertheless I am inclined to regard the lancet-shaped pneu- 

 mococcus, which is identical with the microbe of sputum septicaemia, as the 

 more frequent, and the usual infectious agent of pneumonia, on the ground 

 that this organism is so much more frequently found in the sputum of pneu- 

 monic patients than in that of healthy individuals. This conclusion is 

 further supported by the fact that it has not hitherto been possible to isolate, 

 directly from the rusty sputum, Friedlander's bacilJus." 



The extended researches of Weichselbaum, published in 1886, give strong 

 support to the view that this coccus is the usual infectious agent in croupous 

 pneumonia. He examined, in all, the exudate in one hundred and twenty- 

 nine cases of pneumonia. 



In ninety-four of these cases the micrococcus in question, called by 

 Weichselbaum "diplococcus pneumonias," was obtained (fifty-four times in 

 cultures); in twenty-one cases he obtained a streptococcus, and in nine only 

 was the bacillus of Friedlander encountered. 



Wolf, whose studies were made in Weichselbaifm's laboratory, reported 

 the result of his researches in 1887. He found the "diplococcus pneumonias" 

 in sixty-six out of seventy cases of croupous pneumonia examined, and the 

 "pneumococcus of Friedlander " in three cases. 



Netter, whose paper was published in November, 1887, found Micrococcus 



1 See ray paper published in the American Journal of the Medical Sciences 

 for July, 1886. 



