174 PATHOLOGY 



resistance to the development of the germs, so that pure 

 cultures freed from toxin and injected into animals do 

 not develop. If, however, they are accompanied by 

 saprophytic germs, chemicals, or other material which 

 may cause a lowered vitality of the surrounding tissues, 

 development and toxin formation takes place. So we 

 find wounds into which foreign material has been carried, 

 as wads in blank-cartridge wounds, pieces of clothing, 

 dust, etc., are particularly prone to become the seat of 

 tetanus infection. The uterus (following delivery) and 

 the umbilicus of the newborn furnish fertile fields for 

 infection. 



Morbid Anatomy. There are very few anatomic 

 changes present in this disease. Some congestion of 

 the membranes of the brain and cord are seen, and re- 

 cently some structural alterations of the ganglionic cells 

 of the cord have been described. 



Morbid Physiology. The bacilli remain localized and 

 cause little or no disturbance. All the symptoms are 

 caused by the toxin, which reaches the brain and cord 

 by way of the axis-cylinders of the nerve-trunks and not 

 by way of the blood- and lymph-channels. The toxin 

 has a peculiar affinity for the cells of the central nervous 

 system, and is seemingly harmless to other tissues. 

 Its effect upon the nervous system is similar to strychnin, 

 causing violent spasms of the voluntary muscles. It 

 is eliminated by the urine, which is highly toxic. An 

 antitoxin is elaborated in the blood of infected indi- 



