XXI] PATHOGENIC ORGANISMS 555 



the guinea-pig for some successive transmissions it becomes 

 virulent even for subcutaneous injection ; the same apphes 

 to bacillus coli, bacillus of typhoid, vibrio of Finkler, and 

 others. Particularly bacillus coli can in this way so much 

 increase in virulence that small doses injected subcutaneously 

 cause acute septicsemic infection. 



Some very striking phenomena are shown in these respects 

 by the bacillus coli. The typical bacillus coli cultivated 

 from the intestinal contents of a guinea-pig does not possess 

 towards the guinea-pig greater pathogenic power (as shown 

 by subcutaneous or intraperitoneal injection) than the typical 

 bacillus cultivated from the human intestine. 



Now, occasionally on intraperitoneal injection of a fatal 

 dose of one or the other microbe (bacillus prodigiosus, 

 staphylococcus aureus, vibrio Finkler, or vibrio cholera) 

 after death of the animal (in sixteen to twenty-four hours 

 according to the dose and virulence) the peritoneal fluid 

 contains besides the microbe injected also an abundance of 

 a rapidly motile cylindrical bacillus which in culture proves 

 to be the typical bacillus coli (Klein, Gartner). That this 

 could have been derived from the interior of the intestine 

 only seems clear, but whether it got through the diseased 

 but uninjured wall of the intestine (there has been established 

 severe peritonitis by the microbe injected) or whether during 

 the intraperitoneal injection the intestine has been injured 

 by the cannula of the syringe it is difficult to say, at any 

 rate there is no visible puncture of the intestine to be found. 

 But it must be obvious that if on injection into the peritoneal 

 cavity of say a pure culture of bacillus prodigiosus there 

 should after the death of the animal be found in the peri- 

 toneal exudation, besides the bacillus prodigiosus, a bacillus 

 which possesses all cultural characters of the bacillus coli 

 the conclusion that this latter has got into the peritoneal 



