DIPHTHERIA BACILLUS. 331 



pseudomembranes were produced, and frequently death 

 or paralysis followed, with characteristic lesions. 



In 1887 and 1888 further studies by Loffler, Eoux, 

 and Yersin added to the proof of the dependence of 

 diphtheria on this bacillus. It was found that while 

 no other forms of bacteria were constantly met with, 

 the diphtheria bacilli were present in all characteristic 

 cases of diphtheria, and that these bacilli possessed the 

 morphological, cultural, and pathogenic qualities of 

 those described by Klebs and Loffler. The results of 

 these investigations have since been confirmed by a 

 great number of combined clinical and bacteriological 

 observations both in animals and human beings. A 

 very instructive accidental experiment was carried out 

 under my observation some years ago. One of the 

 laboratory workers unintentionally sucked through a 

 defective pipette a few drops into the mouth of a 

 bouillon culture of a virulent diphtheria bacillus, and 

 two days later characteristic diphtheria of a serious type 

 developed. All the conditions have been fulfilled for 

 diphtheria which are necessary to the most rigid proof 

 of the dependence of an infective disease upon a given 

 micro-organism viz., the constant presence of this 

 organism in the lesions of the disease, the isolation of 

 the organism in pure culture, the reproduction of the 

 essential lesions of the disease in animals and in man 

 by inoculation with pure cultures, the failure to produce 

 all the characteristic lesions of this disease by any other 

 bacteria, and the additional proof of the immunizing 

 value of the specific substances developed in animals 

 subjected to injections of diphtheria toxin. In view of 

 these facts we are now justified in saying that the name 

 diphtheria, or at least primary diphtheria, should be 



