382 
LEONARD PEARSON. 
spores of the tetanus bacillus is trichloride of iodine. This fact 
was discovered by Behring, and has been made use of in a 
number of important experiments. These germs are not only 
resistant to the digestive fluids, but they may even multiply in 
the digestive tract. This accounts for their presence in the 
manure of horses. 
The tetanus bacilli are so widely distributed, and find the 
conditions outside of the living body so favorable to their exis¬ 
tence, that opportunity for infection is abundant, and there are 
few places that are entirely free from this disease, although it is 
far more prevalent in some localities than in others. The man¬ 
ner in which the bacillus is introduced into the living ani¬ 
mal is a matter of considerable moment as regards the danger of 
such inoculation, since the organism will not grow in the pres¬ 
ence of oxygen; all inoculations with the tetanus bacillus are 
not dangerous, but when the organism is introduced deeply into 
the tissues away from the air, or when it is introduced with 
other germs that use up the oxygen in the surrounding parts, 
tetanus may develop. 
The wounds that are especially apt to be followed by the 
development of tetanus are wounds made by objects that have 
been in contact with the earth, and are therefore most apt to 
contain tetanus germs. For instance, pricking of the foot is 
especially dangerous in this respect, and a calk-wound of the 
coronet is also accompanied by considerable danger, as it is 
likely to be made by an object that has been in contact with 
earth and manure, and to be coated with more or less tetanus 
bacilli. A deep puncture with a piece of wood, castration, and 
docking have also been followed in many cases by tetanus. 
The use of clamps in castration was frequently followed by 
tetanus in the olden times, when it was not customary to disin¬ 
fect these instruments. The infectious wound-secretion con¬ 
taining the bacilli and spores of tetanus would in this way be 
carried from one colt 1o another, and the death of a large pro¬ 
portion of the animals castrated by certain operators or in cer¬ 
tain districts was not uncommon. The not rare cases of tetanus 
