76 
BACTERIOLOGY. 
Tetanus 
toxin 
Immunity 
Serum 
treatment 
into spasm, making the entire body rigid. These 
spasms are produced by soluble poisons that are 
formed by the tetanus bacilli at the point of inocula¬ 
tion, and seem to have a special affinity for the tissues 
of the brain and spinal cord. The poisons are also 
formed in the culture media, and are among the most 
powerful known; the poison formed in a bouillon cul¬ 
ture being sufficient to cause death when injected into 
mice in doses of 0.0000005 cubic centimeters. Man 
and the horse are very susceptible to the poison, while 
chickens are able to resist large doses. 
It is possible to immunize animals against the 
tetanus toxin by injecting the poison in very small 
doses and gradually increasing it. After a time the 
animal can withstand large doses- without ill effect. 
The antitoxin is made by injecting horses with ascend¬ 
ing doses of the poison until they are thoroughly im¬ 
munized; then they are bled and the serum, which 
contains the protective substance is used to protect 
human beings. Tetanus antitoxin is used both as a 
prophylactic and a curative agent. For prophylaxis a 
dose of 1000 units is given intramuscularly in all cases 
where wounds have been contaminated with dirt. In 
the United States Army during the war all wounded 
men received tetanus antitoxin at once and another 
dose after ten days. By this means the incidence of 
tetanus in the Army was practically nil. 
For curative purposes tetanus antitoxin must be 
given intraspinally in doses of 3000 to 5000 units and 
repeated if necessary. At the same time the antitoxin 
