DIPHTHERIA. 151 



of the microorganisms are ever found in the blood or deep- 

 seated organs in cases of this disease ; and filtered cultures from 

 which the bacilli have been completely eliminated, when inocu- 

 lated into animals give rise to symptoms identical with those 

 induced by inoculation of the virulent bacilli themselves. 

 Roux and Yersin, by the filtration of cultures through un- 

 glazed porcelain, have been able to separate from the bacilli 

 a toxalbumin which, when injected under the skin of rabbits 

 and guinea-pigs, produces the blood-poisoning, renal and 

 nervous symptoms met with in pure diphtheria. Welch and 

 Abbott have repeated these experiments, and having estab- 

 lished the same facts have come to the same conclusion as to 

 the action of this toxalbumin. 



Subcutaneous inoculations of the diphtheria bacilli will pro- 

 duce death in guinea-pigs in about thirty-six hours. The fol- 

 lowing lesions are found at the autopsy : General oedema at 

 the point of inoculation, with the formation of a false mem- 

 brane. Marked congestion of the adrenal bodies, serous or 

 serosanguinolent effusions in the pleural cavities, and swollen 

 spleen. A few of the bacilli may be found at the point of 

 inoculation and in the fluid of the oedema. In the blood and 

 internal organs no bacilli can be found, showing that the 

 symptoms are purely toxic. 



Roux and Yersin have also been able to produce the false 

 membrane giving rise to the disease, by the inoculation of 

 rabbits and guinea-pigs into the mucous surfaces or into the 

 skin, and they have reproduced in animals the characteristic 

 diphtheria paralysis. This paralysis, best seen in the rabbit, 

 usually begins in the posterior extremities and gradually ex- 

 tends over the whole body, death being caused by paralysia 

 of the heart and respiratory organs. 



Different cultures of diphtheria bacilli, though emanating 

 from equally virulent cases of diphtheria, and grown under 

 the same conditions, show at times a great variation in toxicity. 

 The explanation of this has not been as yet satisfactorily 

 given. But this fact we should remember when testing the 

 efficacy of antitoxins in neutralizing the toxins of diphtheria. 



