THE BACILLUS OF TETANUS. 397 



in the natural disease are very much less favorable, in- 

 asmuch as treatment is usually commenced not shortly 

 after the infection has taken place, but often only on 

 the appearance of tetanic symptoms, when the poison 

 has already diffused itself through the body. 



Tetanus Antitoxin. The tetanus antitoxin is developed 

 in the same manner as the diphtheria antitoxin by 

 inoculating the tetanus toxin in increasing doses into 

 horses. The toxin is produced in bouillon cultures 

 grown anaerobically. After ten or fifteen days the 

 culture fluid is filtered through porcelain, and the germ- 

 free filtrate is used for the inoculations. The horses 

 receive half a c.c. as the initial dose of a toxin of which 

 1 c.c. kills 250,000 grammes of guinea-pig, and along 

 with this a sufficient amount of antitoxin to neutralize 

 it. In five days this dose is doubled, and then every 

 five to seven days larger amounts are given. The dose 

 is increased, as rapidly as the horse s can stand it, until 

 they support 700 to 800 c.c. or more at a single injec- 

 tion. After some months of this treatment the blood 

 of the horse contains the antitoxin in sufficient amount 

 for therapeutic use. When the animals 7 temperatures 

 are normal and they have recovered from the dose of 

 toxin last given, they are bled into sterile flasks and 

 the serum collected. 



Technique of Testing Antitoxin Serum for Value in 

 Antitoxin. Tetanus antitoxin is tested exactly in the 

 same manner as diphtheria antitoxin, except that the 

 standard unit is different. The test toxin used in the 

 German method is one of which 1 gramme destroys 

 150,000,000 grammes of mouse. This is dissolved in 

 33 J c.c. of 10 per cent. NaCl solution. Ten times the 

 amount of antitoxic serum which neutralizes 1 c.c. of 



