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 anaérobically. 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 ce. 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 horscs can stand it, until 
they support 700 to 800 ¢.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’ 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 
334 c.c. of 10 per cent. NaCl solution. Ten times the 
amount of antitoxic serum which neutralizes 1 c.c. of 
