Medical Officers of the Army of India.
39
within the organism which they act upon. But this by no means necessarily
follows from the data. The phenomena presented by individual cases of the
disease and those attending its epidemic diffusion leave little room to doubt
that it is essentially due to the action of poisonous materials which have been
elaborated by an organised agency, but they most certainly do not conclusively
show that the process of manufacture is carried out within the bodies of those
upon whom they act. On the contrary, there are many phenomena which strong-
ly suggest that the manufacture occurs in the environment, and that the initiation
of the morbid state is due to the ingestion of the elaborated poison, and not of the
factors which elaborate it. Did the manufacture of the poison and the multi-
plication of the factors producing it go on within the bodies of the sick, it would
be almost impossible to explain that necessity of local predisposition for the de-
velopment of epidemics, the existence of which has been so clearly demonstrated
by Professor von Pettenkofer. In connection with diseases which are due to
the action of organisms whose proper site for multiplication is the bodies of
those affected by them, we do not find any examples of localities in which relative
or complete exemption from any diffusion of disease continues to manifes
t itself in spite of repeated importation of individual cases. But in the case of
cholera, phenomena of local exemption on a larger or smaller scale are con-
stantly presenting themselves to observation. In certain cases it may be possi-
ble to ascribe the exemption to an absence of personal predisposition on the
part of those living within the area in which it manifests itself, but there are other
instances in which any such explanation is entirely insufficient. Any one who
has had a prolonged experience of the phenomena which are presented by the
hospitals in Calcutta is aware that any diffusion of cholera within them has
always been a most exceptional occurrence in spite of entire absence or very
imperfect enforcement of any measures for isolating the sick, and that when cases
of cholera do originate within them, they do so either as solitary cases or as
units in small local epidemics originating quite apart from any traceable connec-
tion with imported cases. Now, the transitory nature of the population of any
hospital renders it at all events extremely improbable that the phenomena of
normal localised exemption and of exceptional localised occurrence of the disease
are due to the absence or presence of personal predisposition, and, excluding
this, the only explanation is that they are connected with the presence of local
conditions which normally are of a nature to prevent the manufacture and
multiplication of the cause of cholera, but which exceptionally become so far
altered as to allow of their occurrence.
The practical benefits which attend the temporary abandonment of localities
in which cholera has established itself—the phenomena which in India attend the
system of sending troops or prisoners out into so-called cholera-camps on the
outbreak of the disease in a station or jail—are all in favour of the view that the
essential site of the development and multiplication of the specific cause of the