DIPHTHERIA BACILLUS. 3855 
Léoffler bacilli. These will be referred to further under 
their respective organisms. 
The Transmission of Diphtheria. The possibility of 
the transmission of diphtheria from animals to man 
cannot be disputed, for cats and many animals can be 
infected, but there are no authentic cases of such 
transmission on record. So-called diphtheritic disease 
in animals and birds is usually due to other micro- 
organisms than the diphtheria bacilli. Diphtheritic 
infection, however, can generally be traced, directly or 
indirectly, to its source; though there are undoubtedly 
some cases of diphtheria in which we cannot determine 
the source of the infection, for we have no reason to 
believe that diphtheria is ever spontaneous. 
Let us consider some of the means by which the dis- 
ease may be communicated. In actual experiment the 
bacilli have been observed to remain virulent in bits 
of dried membrane bv Loffler for fourteen weeks, 
by us for seventeen weeks, and by Roux and Yersin 
for twenty weeks. Dried on silk threads Abel reports 
that they may sometimes live one hundred and seventy- 
two days, and upon a child’s plaything which had been 
~ kept in a dark place they lived for five months. The 
virulent bacilli have been found on soiled bedding or 
clothing of a diphtheria patient, on drinking-cups, 
shoes, hair, slate-pencils, etc. Beside these sources 
of infection by which the disease may be indirectly 
transmitted, virulent bacilli may be directly received 
from the pseudomembrane, exudate, or discharges of 
diphtheria patients; from the secretions of the nose 
and throat of convalescent cases of diphtheria in which 
the virulent bacilli persist; and from the healthy 
throats of individuals who acquired the bacilli from 
