V. 



PYOGENIC BACTERIA. 



THE demonstration made by Ogston, Rosenbach, Passet, and 

 others that micrococci are constantly present in the pus of acute 

 abscesses, led to the inference that there can be no pus formation in 

 the absence of microorganisms of this class. But it is now well 

 established, by the experiments of Grawitz, De Bary, Steinhaus, 

 Scheurlen, Kaufmann, and others, that this inference was a mis- 

 taken one, and that certain chemical substances introduced beneath 

 the skin give rise to pus formation quite independently of bacteria. 

 Among the substances tested which have given a positive result are 

 nitrate of silver, oil of turpentine, strong liquor ammoniae, cada- 

 verin, etc. The demonstration has also been made by numerous in- 

 vestigators that cultures of pus cocci, when sterilized by heat, still 

 give rise to pus formation when injected subcutaneously. This was 

 first established by Pasteur in 1878, who found that sterilized cul- 

 tures of his " microbe generateur du pus " induced suppuration as 

 well as cultures containing the living microbe. This fact lias since 

 been confirmed, as regards the pus staphylococci and various bacilli, 

 by a number of bacteriologists. Wyssokowitsch produced abscesses 

 containing sterile pus by injecting subcutaneously agar cultures of 

 the anthrax bacillus sterilized by heat. Buchner obtained similar 

 results in a series of forty experiments from the injection of steril- 

 ized cultures of Friedlander's bacillus (" pneumococcus "), and has 

 shown that the pus-forming property belongs to the bacterial cells 

 and not to a soluble chemical substance produced by them. When 

 cultures were filtered by means of a Chamberlain filter the clear 

 fluid which passed through the porous porcelain was without effect, 

 while the dead bacteria retained by the filter produced aseptic pus 

 infiltration in the subcutaneous tissues within forty-eight hours 

 after having been injected. Subsequent experiments gave similar 

 results with seventeen different species tested, including Staphylo- 

 coccus pyogenes aureus, Staphylococcus cereus flavus, Sarcina auran- 

 tiaca, Bacillus prodigiosus, Bacillus Fitzianus, Bacillus subtilis, 

 Bacillus coli communis, Bacillus acidi lactici, etc. From the experi- 



