110 STUDY AND IDENTIFICATION OF BACTERIA 



In addition to having an endotoxin, it produces a soluble toxin similar to diph- 

 theria toxin. This toxin differs from those of diphtheria and tetanus in that it can 

 stand a temperature of 100 C., while those of diphtheria and tetanus are destroyed 

 at about 65 C. The fact that the union between toxin and antitoxin is only of a 

 binding, neutralizing nature is best shown by taking a mixture of pyocyaneus toxin 

 and antitoxin which is innocuous and heating it. This destroys the antitoxin, but 

 does not injure the toxin. We now find that the original toxicity has returned. The 

 antitoxins of diphtheria and tetanus are more stable than the corresponding toxins; 

 hence, this experiment would be impossible with them, as upon heating we should 

 first destroy the toxin. 



On account of the frequent association of B. pyocyaneus with other 

 organisms of better recognized pathogenicity it has until more recently 

 been considered rather harmless; this view can no longer be entertained 

 as it is frequently the sole cause of middle-ear inflammations, intestinal 

 disorders and possibly at times of septicaemia. 



FIG. 35. Bacillus pyocyaneus. (Kolle and Wassermenn.) 



B. prodigiosus. 'This is a very small coccobacillus which shows mo- 

 tility in young bouillon cultures. It is Gram negative. The colonies 

 on agar or other solid media show a rich red color. The pigment only de- 

 velops at room temperature; it is absent in cultures taken out of the 

 incubator. The B. prodigiosus is frequently found on foodstuffs, 

 especially bread, where it may simulate blood. It liquefies gelatin rap- 

 idly and gives a diffuse turbidity to bouillon. It is probable that B. 

 indicus and B. kilensis are strains of B. prodigiosus. 



Coley's fluid, which has been used in cases of inoperable sarcoma and other 

 malignant growths, is a culture prepared by growing very virulent streptococci in 



