CHROMOGfiNIC BACILLI. 93 



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 innocu- 

 ous 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 corre- 

 sponding toxins; hence, this experiment would be impossible with 

 them, as upon heating we should fir >t destroy the toxin. 



B. prodigiosus. This is a very small coccobacillus which shows 

 motility in young bouillon cultures. It is Gram negative. The 

 colonies on agar or other solid media show a rich red color. The 

 pigment only develops at room temperature; it is absent in cultures 

 taken out of the incubator. The B. prodigiosus is frequently found 

 on food stuffs, especially bread, where it may simulate blood. It 

 liquefies gelatin rapidly 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 bouillon for ten days. This streptococcus 

 culture is now inoculated with B. prodigiosus, and after another ten 

 days the mixed culture is killed by heat at 60 C. and the sterile 

 product injected. Coley injected about one-twentieth of a c.c. of 

 this vaccine. 



