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DIAGNOSIS AND PATHOLOGICAL ANATOMY. 479
lunatics where, as at Gheel, the patients enjoyed a certain
amount of freedom combined with careful supervision and
nursing, and were provided with work suited to their con­
ditions.
In no department of pathology, however, were the
changes greater than in that of infectious diseases. New
forms of disease were now recognized which had previously
escaped observation, and those affections already on the
nosological list were more correctly and accurately dis­
tinguished from one another, especially in respect of their
aetiology. The nature of the infective material of disease,
its origin within or without the human body, its develop­
ment in different media, its relation to climate, soil, etc.,
the duration of its virulence, and the possibility of its being
transported from place to place were all subjects carefully
investigated.
Asiatic cholera in the 19th century outstepped the limits
of its native land, and spread itself over the globe. The
grievous loss of human life which its presence entailed
rendered it incumbent upon the doctors to examine into
the causes and real nature of this disease. The remarkable
relations existing between its origin and extension on the
one hand, and conditions of the soil on the other, were
the subject of observation. With the discovery of the
comma-bacillus, made not long since, it would seem that the
real and essential cause of the disease has at last been
found.
Yellow fever, which had often been brought to Europe,
was carefully studied, as also were other exotic diseases,
such as beriberi.
The appearance of cerebro-spinal meningitis in an
epidemic form directed public attention to this previously
unknown disease.
At the same time enlightened views began to prevail on
many other diseases. The conception of typhus, a term
at first chiefly of symptomatological significance and lend­
ing itself to qualification according to the prevailing