DIPHTHERIA. 213 



Relations of the Bacilli to Diphtheria in Human 

 Beings. The diphtheria-bacillus may be found in all cases 

 of diphtheria in the diphtheric membrane, and in cases of 

 diphtheria of the tonsils throughout the cavity of the 

 mouth. It lies superficially, usually in large number ; it 

 rarely penetrates deeply. In the bodies of patients suffer- 

 ing from diphtheria the bacillus has almost never been found 

 at any other place than in the false membrane, and 

 especially never in the blood. Only in the bodies of 

 patients dead of diphtheria has it been detected on several 

 occasions also in the blood and in the viscera. Diphtheria 

 in human beings must thus be viewed as a toxic infectious 

 disease. The bacillus is responsible only for the local pro- 

 cess ; the constitutional manifestations (fever, palsy, etc.) 

 being dependent in human beings also upon absorption of 

 the toxic metabolic products of the bacillus. The local 

 action of the diphtheria -bacillus consists in necrosis of the 

 epithelium and of the uppermost layer of the mucosa, 

 which are thus converted into diphtheric membrane. This 

 true diphtheric inflammatory process does not occur apart 

 from the action of certain poisons, as, for instance, diph- 

 theria of the large intestine in conjunction with mercurial 

 poisoning in the absence of diphtheria-bacilli. The diph- 

 theria-bacillus, however, by no means always gives rise to 

 such a necrotic inflammatory process, when present in the 

 body. The organism has been found repeatedly also in 

 cases of fibrinous rhinitis and of croupous conjunctivitis, the 

 latter being clinically quite different from diphtheria of the 

 conjunctiva. Under these conditions the diphtheria-bacilli 

 have simply given rise to a croupous exudation without 

 necrosis. Finally, Loffler has found virulent diphtheria- 

 bacilli in the mouth of a healthy child, an observation that 

 has since been repeated by others. The diphtheria-bacillus 

 may, thus, under certain conditions, vegetate upon mucous 

 membranes in a virulent state, without occasioning disease 

 of those structures. 



Mixed Infection in Human Beings. The diphtheria- 

 bacillus is rarely found alone in the membranes, being 

 usually associated with streptococci, also with staphylococci, 

 pneumococci, and coli commune. It is almost certain that 

 the severe purulent and septic manifestations observed in 

 some cases of diphtheria are to be attributed to such mixed 

 infection with especially virulent streptococci. It is a matter 



