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Annual Report of the Medical Officer of Health—1866—7. 17
I must now call your attention to the epidemic which visited us last year, but from
which happily our district suffered so little. Cholera, whatever may be its cause, has lost
none of its old malignancy. We had flattered ourselves that such was not the case, and
reasonably so, for with each attack its mortality had decreased. In the three epidemics
which have visited London, the deaths to every 10,000 of the population were 62, 43, and
18. In the East Districts, however, during the recent epidemic the deaths were 64 to every
10,000. Its apparent decline in this and other districts may, I think, without assumption,
be attributed as due to sanitary improvements. The origin of cholera, though still very
obscure, has had some light thrown upon it by the late outbreak, and by that of the cattle
plague. Cholera is a morbid poison that enters into the blood either by the way of the
stomach or lungs, and pollutes it. It is probably a living organism, consisting of "germinal
matter, or living cells, possessing individuality, which are capable of preserving their
activity for a certain time outside the living organism, of adhering to material objects, and
of being carried from one place to another by currents of air " and by water. " By living
cells is not meant living, in the sense in which an animal, or even a low form of infusoria
I lives; but living as a seed, or-as vaccine matter, even when dried, may be living, inasmuch
as it still possesses reproductive vitality." When once this poison is active and prevalent,
season and temperature seem to exercise little influence over it. Neither climate nor season,"
says a modem writer, "nor earth nor ocean has power to arrest its course, or alter its
features. It was equally destructive at St. Petersburg and Moscow as in India; as fierce
and incurable amongst the snows of Russia, as in the sun-burnt regions of India; as
destructive in the vapoury districts of Burmah as in the parched provinces of Hindostan."
Observation has, however, favoured the conclusion that heat, moisture, and a complete
stagnation of the air are most conducive to its spread. Mists, from their nature, afford a
most favourable medium for carrying about in solution, or otherwise, the emanations that
are exhaled from the earth, as well as whatever organisms may be present. Hence probably
the origin of the blue mist, about which we have heard so much. Cholera has
prevailed most in low lying districts, owing chiefly to the stagnancy of the air, and to the
necessary concentration of foul emanations. Currents of air may be rushing along high
over-head, whilst all below is calm and unruffled. Besides, the poison germ itself may be
heavier than the air like that of malaria, and so fall down and settle. That these germs
are invisible need occasion no surprise, for what a multitude of floating particles of matter
will a sun-beam reveal, which before were unseen. The distance to which they may travel
we cannot measure, inasmuch as such a heavy material as sand can be borne along hundreds
of miles, according to a statement made by Dr. Mc Leod in his Eastern Travels. " Whilst
sailing along," he says, "parallel to the coast of Africa, and having been long out of sight
of land, the weather rigging of the ship was all brown with sand which had adhered to the
tar; and this was only visible on the side of the ropes next the desert." In Nova Scotia,
Canada, and in other countries where pine forests of any considerable extent are met with,
there is an annual fall of pollen. When the trees are in full bloom, the pollen fills the air,
and only becomes visible by its coating the surface of the lakes and ponds, and quiet bays of
the sea; it finds its way down the water spouts into cisterns and tanks. Now it is very
reasonable to suppose that in a similar manner the cholera poison may float about, falling
here and there, in larger or smaller quantities, as currents of air or other circumstances
may direct, although at no time becoming visible. There can be no doubt but that it is