xxi] PATHOGENIC OkGANlSMS 563 



do follow. This is particularly the case if recent Agar or 

 serum cultures be used instead of gelatine culture, or if in 

 addition to the gelatine cultures diphtheria toxin — from an 

 active broth culture — be injected. In such a case the animal, 

 presumably on account of the toxin present (evidently not 

 present in the gelatine, growth), soon sickens, and is found 

 dead in thirty-six to forty-eight hours or later. On examining 

 the peritoneal fluid in such, a case it will be seen that very 

 few diphtheria bacilli are demonstrable, either in cover-glass 

 specimens or by culture ; in the latter case a drop of the 

 fluid yields only a few colonies. But if we look to the 

 omentum next to the large curvature of the stomach we 

 find masses of lymph, which examined under the micro- 

 scope show aggregations of leucocytes all filled with diph- 

 theria bacilli, some well preserved, others in fragments ; 

 between the leucocytes are also large numbers of free 

 bacilli. In these cases then, when the resistance of the 

 peritoneum — so perfect against the bacilli of gelatine cul- 

 ture — has broken down and been overcome, presumably by 

 the additional introduction of toxin, we find numbers of 

 phagocytes, whereas in the other case when the resistance 

 of the peritoneum has successfully been' maintained — e.g., in 

 the case of using bacilli of gelatine culture — there is no sign 

 of phagocytes. 



To the same group of phenomena belongs the occurrence 

 of numerous phagocytes, i.e., leucocytes filled with the 

 microbe, in cases when the injection has produced fatal 

 infection and where there is just the reverse of immunity 

 either of a particular tissue or of the animal as, for instance, 

 in fatal mouse septicaemia, in fatal swine erysipelas, when the 

 presence of leucocytes filled with living bacilli is a con- 

 spicuous feature. Add to this the same condition in the 

 leucocytes of the purulent secretion in Koch's Egyptian 



002 



