DIPHTHERIA BACILLUS. 349 



the action of these bacilli. At autopsy the bacilli are 

 usually found more or less abundantly in the blood and 

 internal organs. In this very same location, however, 

 diphtheria bacilli are found of very low toxic power, 

 so that here, again, we cannot assert that these xerosic 

 bacilli have not come from true diphtheria stock. 



Location of Diphtheritic Inflammations and Viru- 

 lence of Bacilli. Virulent bacilli produce and are 

 found not only in pseudomembranous inflammations 

 of the fauces, larynx, and nasal cavities, but also occa- 

 sionally in membranous affections of the skin, vagina, 

 rectum, conjunctiva, nose, and ear (simple mem- 

 branous rhinitis and otitis media). From the severity 

 of an isolated case the virulence of the bacilli cannot be 

 accurately determined. The most virulent bacillus I 

 have ever found was obtained from a mild case of diph- 

 theria simulating tonsillitis. Another case, however, 

 infected by this bacillus proved to be very severe. In 

 localized epidemics the average severity of the cases 

 probably indicates roughly the virulence of the bacillus 

 causing the infection, as here the individual susceptibil- 

 ity of the different persons infected would, in all likeli- 

 hood, when taken together, be similar to that of other 

 groups; but even in this instance special conditions of 

 climate, food, or race may influence certain localities. 

 Moreover, the bacteria associated with the diphtheria 

 bacilli, and which are liable to be transmitted with them, 

 may influence the severity of and the complications 

 arising in the cases. 



Virulent Bacilli in Healthy Throats. Fully virulent 

 bacilli have frequently been found in healthy throats 

 of persons who have been brought in direct contact 

 with diphtheria patients or infected clothing without 



