I
There are several classes of experiments. Some are in the field of
pure research, not having for their object any immediate benefit to
man or animals. Experiments of this nature were carried on some years
ago in work on bubonic plague among rodents in California. It was
discovered that ground squirrels have a disease similar to plague and
yet distinctly different. By a long series of experiments it was found
that monkeys are susceptible to this disease, and it was predicted
that eventually cases would be found in man. As a result of this
work a bacteriologist in Cincinnati was able to identify the disease
in persons in his own vicinity. Another investigator found it among
persons in Utah, and showed that it is carried from infected rabbits
and ground squirrels by biting insects. It also was shown that the
disease is widespread over the United States. With this knowledge of
the means of transmission of the disease it is comparatively easy to
prevent the infection of man.