DIPHTHERIA BACILLUS. 355 



Loffler 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 by 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 drin king-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 pseudo membrane, 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 



