x, B,1 Ruediger: Preparation of Tetanus Antitoxin 49 

Fic. 51. Chart showing the antitoxin curve for horse 5. Units per eubie centimeter by months. 
HORSE 6 
Immunization of horse 6 was begun on November 10, 1913. 
It was fortified with 2,000 units of tetanus antitoxin, 1,000 units 
of which were injected on November 10, 1913, and 1,000 units, 
on November 24, 1913. Beginning with a dose of 1 cubic 
centimeter, tetanus toxin was injected at intervals of a week 
and the doses were increased more gradually than had been the 
practice previously. A test bleeding was made on April 6, 1914, 
and the serum was found to contain 250 units of antitoxin per 
cubic centimeter. The horse was bled 6 liters on April 14, 1914, 
and again 6 liters on April 18, 1914, the serum testing a little 
more than 250 units of antitoxin per cubic centimeter each time. 
The injections of toxin were continued. Eight liters of blood 
were withdrawn on May 26, 1914, from which about 3.2 liters 
of serum were obtained, which tested about 300 units per cubic 
centimeter. Four injections of toxin were given during June, 
1914. On June 29, 1914, the horse was bled 5 liters; the 
serum contained 500 units of antitoxin per. cubic centimeter. 
On July 3, 1914, the horse was bled to death; 12 liters of blood 
were obtained this time. The serum contained more than 450, 
but less than 500, units of antitoxin per cubic centimeter. 
Horse 6 received in all 9,578.5 cubic centimeters of tetanus 
toxin and furnished 37 liters of blood. It produced about 14.8 
liters of antitetanic serum or 5,320,000 units of tetanus anti- 
132195——4 
