72 BACTERIOLOGY. 



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 c.c. Man and the horse are 

 very susceptible to the poison, while chickens are able 

 to resist large doses. 



immunity It is possible to immunize animals against the 



tetanus toxin by injecting the poison in very small 

 doses and gradually increasing it. In time the 

 animal can withstand large doses without ill effect. 

 The antitoxin for tetanus is made by injecting the 

 poison in ascending doses into horses until they are 

 thoroughly immunized; then they are bled and the 

 serum, which contains the protective substance, is used 

 to inject into human beings. The use of tetanus anti- 

 toxin has not been attended with as much success as 

 the antitoxin of diphtheria. When the symptoms of 

 lockjaw develop it means that the toxin has already 

 attacked the brain and spinal cord ; so the antitoxin is 

 of little use. To be effective it must be given at the 

 time of the infection or shortly after. 



THE GLANDERS BACILLUS (BACILLUS MALLEI). 



Glanders is a malady which occurs principally 

 among horses, but dogs, cats, sheep, and swine are 



