TETANUS. 
383 
that occur without external injury are explained by the assump¬ 
tion that infection has taken place through a wound that was so 
small as to escape notice, or that infection occurred through 
the mucous membrane of the intestinal canal. 
The disease, tetanus, is caused by the tetanus bacillus by 
means of a toxin, or ptomaine, that is developed by this germ. 
This substance is produced by the germs at the point of inocu¬ 
lation. It is carried by the circulation to all parts of the body, 
and its action on the central nervous system is such as to pro¬ 
duce the muscular spasms that are characteristic of the disease. 
The toxin of tetanus is also produced when the germ is grown 
in culture-media in the laboratory, and it has been found that 
the injection of a small quantity of toxin that is entirely free 
from living organisms will produce the symptoms of tetanus. 
The power of this toxin is extraordinary, and but a very small 
quantity of it will produce death. 
The rapidity also with which the toxin is developed is as¬ 
tonishing. Kitasato has found, for instance, that when mice 
are inoculated at the root of the tail, and afterward the skin and 
subcutaneous tissues around the inoculation are removed and 
cauterized, the treatment is without avail unless it is performed 
within one hour after the inoculation. In cases of tetanus toxin 
is found in the muscle-juice, the blood, the urine, and in the 
milk. As the toxin gradually passes from the point of inocula¬ 
tion, where it is developed, into the general circulation, it is 
noticed that rigidity of the muscles begins in the inoculated 
member or part of the body and gradually extends to the more 
distant portions. It has been shown by Nocard that by the 
time the symptoms of tetanus appear in the horse the saturation 
of the tissues with tetanus toxin is quite general, and the 
amount of toxin contained in the body at that time is enor¬ 
mous. 
The bacilli themselves never enter the blood, and, of course, 
cannot pass into the circulation, and after they have elaborated 
enough toxin to cause death the post-mortem appearances, as is 
well known, are about normal, with the exception of the sup- 
