PATHOGENIC PROPERTIES. 337 



An affection may be produced by the inoculation of 

 certain animals that is in all respects identical with the 

 disease diphtheria as it exists in man. If one open the 

 trachea of a kitten and rub upon the mucous mem- 

 brane a small portion of a pure culture of this organ- 

 ism, the death of the animal usually ensues in from two 

 to four days. At autopsy the wound will be found 

 covered with a grayish, adherent, necrotic, distinctly 

 diphtheritic layer. Around the wound the subcuta- 

 neous tissues will be oedematous. The lymphatic glands 

 at the angle of the jaws will be swollen and reddened. 

 The mucous membrane of the trachea at the point upon 

 which the bacilli were deposited will be covered with 

 a tolerably firm, grayish-white, loosely attached pseudo- 

 membrane in all respects identical with the croupous 

 membrane observed in the same situation in cases of 

 human diphtheria. In the pseudo-membrane and in 

 the oedematous fluid about the skin-wound bacillus 

 diphtlierice may be found both in cover-slips and in 

 cultures. 



From what we have seen — the localization of the 

 bacilli at the point of inoculation, their absence from the 

 internal organs, and the changes brought about in the 

 cellular elements of the internal organs — there is but 

 one interpretation for this process, viz., that it is due to 

 the production of a soluble poison by the bacteria grow- 

 ing at the seat of inoculation, which, gaining access to 

 the circulation, produces the changes that we observe in 

 the tissues of the internal viscera. 



This poison has been isolated from cultures of the 

 bacillus diphtheriw, and is found to belong, not to the 

 crystallizable ptomaines, but to the toxic albumins — 

 bodies which, in their chemical composition, are analo- 



