78 
WORLD OF INVISIBLE LIFE 
What is 
lochjaw? 
the name. It frequently results from deep, 
dirty cuts or wounds, such as those caused by 
a rusty nail, or by the explosion of fireworks 
and toy pistols. 
This disease is the work of a slender, rod¬ 
shaped germ called tetanus. It is present every¬ 
where in the soil, in dust, in mud, in water, 
and it grows without harmful effects in the 
intestines of horses and other animals. Human 
bodies are not its natural home; it gets into 
them only accidentally, and causes trouble only 
under special circumstances. It grows in deep 
wounds into which dirt, as well as other mi¬ 
crobes, has been pushed. Its growth there 
depends on the presence of other microbes. 
It does not spread into either the blood-stream 
or the tissues, but multiplies in the wound itself 
and produces a poison which attacks only the 
nerves. The poison travels along the nerves to 
the central nervous system, where it causes the 
muscular cramps which betray its presence. 
Once the poison gets into the nerves, it is almost 
always fatal. But science has discovered an 
