DIPHTHERIA BACILLUS 131 



guinea-pig; it should be grown in alkaline sugar bouillon and 

 tested in two days for acid. The xerosis and Hoffman's 

 bacilli are not pathogenic for guinea-pigs. 



Products. But it is not the mere presence of the bacillus 

 that gives rise to trouble: certain products which generate it 

 get into the system and produce the severe constitutional 

 symptoms. 



Toxins of Diphtheria. Roux and Yersin, in 1888, discov- 

 ered the toxin and showed that the injection of the filtered 

 culture bouillon (that is, freed of all diphtheria bacilli) gave 

 rise to the same palsies as when the bacilli themselves were 

 introduced. 



The toxins may be separated from three-weeks-old bouillon 

 cultures by filtration. They are not albumins and are very 

 complex. Ehrlich claims three forms: one he calls toxone; 

 the other, toxin; the toxone produces paralytic symptoms 

 and appears to be less affected by antitoxin; the third, toxoid, 

 combines with antitoxin. The toxins are highly poisonous 

 o.oo i c.c. may be sufficient to kill a guinea-pig in less than 

 twenty-four hours. The substance is unstable, losing its toxic 

 power gradually. Heating at 58 C. for two hours is destruc- 

 tive, but drying renders it more stable. Direct sunlight 

 destroys its power in a few 7 hours. Boiling in five minutes. 

 If kept cold and in the dark, it may remain active two years. 

 Alcohol and calcium chlorid precipitate the toxic element. 



Antitoxin. Behring, in 1890, found that animals rendered 

 immune had a principle in their blood that was antagonistic 

 to the development of the toxin. 



Immunity. Brieger and Frankel, by injecting 10 to 20 c.c. 

 of a three-weeks-old culture of diphtheria bacilli which had 

 been heated at 70 C. for one hour, produced an immunity in 

 guinea-pigs against the virulent form. This active principle 

 is unknown chemically, but has been called antitoxin. 



The toxin generated by the germ is supposed to be neutral- 

 ized by the antitoxin and prevented from injuring the body 

 tissues. The value of antitoxin in diphtheria seems to be 

 established beyond a doubt, and it is the claim of eminent 



