346 MANUAL OF BACTERIOLOGY. 



pression is used in an anatomical sense, meaning that a fibrin- 

 ous pseudomembrane has formed, extending deeply into the 

 tissues, which is not necessarily caused by the diphtheria 

 bacillus. 



The diphtheria bacillus is usually found associated with 

 other pathogenic bacteria in cases of diphtheria. The pus 

 cocci and the pneumococcus very frequently complicate the 

 disease. It seems that the diphtheria bacillus may be either 

 the cause of the primary disease and prepare the way for sec- 

 ondary invasion, or on the other hand it may follow or ac- 

 company a primary infection of some other organism. In 

 other words, cases starting as diphtheria may, and usually do 

 become complicated by pus coccus invasion, or cases starting 

 pus coccus infection or as measles. or scarlet fever or pneu- 

 monia may be complicated by a secondary infection with the 

 diphtheria bacillus 



In cases of diphtheria in man,* the diphtheria bacillus is 

 generally found limited to the vicinity of the pseudomembrane, 

 and at autopsies it is not usually found in the internal viscera, 

 excepting in the lungs, where diphtheria bacilli may or may not 

 be present when diphtheria is complicated with bronchopneu- 

 monia. The general symptoms of the disease, including the 

 paralysis which sometimes follows it, are due to the toxins 

 produced by the bacilli in the throat. 



Diphtheria Antitoxin.^ It is necessary first to obtain the toxin produced by 

 diphtheria bacilli in a concentrated form. For this purpose virulent diphtheria 

 baccilli are cultivated in alkaline, sugar-free bouillon, in flasks plugged with 

 cotton, exposing a large surface to the air. Park % finds that the presence of 

 muscle-sugar makes no difference, provided the broth is made sufficiently 

 alkaline to neutralize the acid formed by the fermentation of the sugar, and 



* For a full study of the lesions of diphtheria see the Monograph of Council- 

 man, Mallory and Pearce. Boston. 1901. 



fSee articles by Park, A. Williams, Atkinson and T. Smith. Journal of 

 Experimental Medicine. Vol. I., p. 164; Vol. III., p. 513; Vol. IV., pp. 373 

 and 649. Journal Medical Research. Vol. IX., p. 173. 



J Park. Loc. cit. p. 194. 



