130 THE AMERICAN MONTHLY [May 
subsequent period. This, Mr, Nelson said, had been his 
frequent experience during the quarter of a century he 
had been actively engaged in microscopical work. 
Does Rabies Originate Spontaneously ? 
D. E. SALMON, D. Y. M. 
Most of the older writers on rabies, those whose writ- 
ings appeared before 1865, admitted that the disease 
might develop spontaneously in the bodies of certain an- 
imals as a result of certain conditions of life and atmos- 
pheric influences. These same writers believed that most 
other contagious diseases frequently originated in the 
same manner. It was a time when the spontaneous gen- 
eration of many living things was frequently admitted, 
and when the ignorance of the nature of all kinds of con- 
tagion, with the exception of the larger animal parasites, 
was complete and impenetrable. Science had not yet 
definitely passed upon the doctrine of the spontaneous 
and continuous generation of living matter. 
It was not a very long time before this when it was be- 
lieved that the mite which causes scabies or itch was con- 
tinuously developed spontaneously, and that it was folly 
for people to try to protect themselves from this disease. 
About the same time, or possibly a little earlier, at was 
thought that lice were spontaneously developed, and that 
both the domesticated animals and mankind were doom- 
ed to suffer from them for all time. Still earlier there 
was a common belief that crocodiles and other animal life 
developed spontaneously from the mud of the rivers and — 
lakes in which they were found. 
The study of natural history and the progress of sci- 
ence disproved one by one these ancient beliefs, and made 
it clear that all animals developed from pre-existing an- 
imals of the samekind. Even lice and the mites of scabies — 
were found to be subject to this invariable law of nature, 
