380 BACTERIA IN DIPHTHERIA. 



The researches of Behring show that the blood of immune ani- 

 mals contains a substance which neutralizes the toxic product con- 

 tained in virulent cultures of the diphtheria bacillus. This effect is 

 said to be produced when blood from such an animal is added to a 

 filtered culture without the body, as well as when the culture is in- 

 jected into the living animal. This remarkable discovery has al- 

 ready been utilized for the treatment of diphtheria in man with most 

 brilliant results. The method of preparing the diphtheria "anti- 

 toxin " is given in the writer's recent work on " Immunity, Pro- 

 tective Inoculations, and Serum-Therapy." 



According to Roux and Yersin, " attenuated varieties " of the 

 diphtheria bacillus may be obtained by cultivating it at a temperature 

 of 30.5 to 40 C. in a current of air ; and these authors suggest that 

 a similar attenuation of pathogenic power may occur in the fauces of 

 convalescents from the disease, and that possibly the similar non- 

 pathogenic bacilli which have been described by various investiga- 

 tors have originated in this way from the true diphtheria bacillus. 

 These authors further state, in favor of this view, that from diphtheri- 

 tic false membrane, preserved by them in a desiccated condition for 

 five months, they obtained numerous colonies of the bacillus in ques- 

 tion, but that the cultures were destitute of pathogenic virulence. 

 They say: 



" It is then possible, by commencing with a virulent bacillus of 

 diphtheria, to obtain artificially a bacillus without virulence, quite 

 similar to the attenuated bacilli which may be obtained from a benign 

 diphtheritic angina, or even- from the mouth of certain persons in 

 good health. This microbe, obtained artificially, resembles com- 

 pletely the pseudo-diphtheritic bacillus ; like it, it grows more abun- 

 dantly at a low temperature; it renders bouillon more rapidly alkaline; 

 it grows with difficulty in the absence of oxygen." 

 % 



48. PSEUDO-DIPHTHERITIC BACILLUS. 



Loffler, Von Hoffmann, and others have reported finding bacilli 

 which closely resemble the Bacillus diphtherias, but which differ 

 IVoiu it chiefly in being non-pathogenic. The following account we 

 take from the latest paper upon the s-ubject by Roux and Yersin 

 1 1 roisieme memoire, 1800). 



Found by Roux and Yersin in mucus from the pharynx and ton- 

 sils of children from forty-five children in Paris hospitals, suffering 

 I'n.m various affections, not diphtheritic, fifteen times; from fifty- 

 nine healthy children in a villa-o school on the seaboard, twenty-six 

 times. Of six children with a simple angina but two furnished cul- 

 farea of this bacillus, while it was obtained in fiveoutof seven casea 

 of measles. 



