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 
