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GEOGEAPHICAL DISTRIBUTION OF CHOLERA. 259 dicate rational means by which nations may be saved from its deadly influence, and cholera confined to its natural limits, if not, in the course of time, destroyed.

We may probably most conveniently consider this part of our subject under three headings:

I. As to the circumstances of those countries which have as yet remained free from cholera.

II. We may attempt to define the endemic area of the disease.

III. We may trace the routes cholera has pursued in its extension from its endemic area over the world.

I. With regard to the distribution of the disease, we have Dr. Gavin Milroy's authority for stating that the only countries which have up to the present time remained free from cholera are, Australia, New Zealand, and the other islands of the Pacific; the Cape of Good Hope and its adjoining settlements, the West coast of Africa from the Cape as far northward as Gambia, including the islands of St. Helena and Ascension; the Azores, Bermuda, Iceland, the Faroe, and also the Orkney and Shetland islands, and lastly the western coast of South America.

But even in India we find that the inhabitants of certain localities have escaped the influence of cholera in a very remarkable manner. For instance, Dr. W. J. Moore assures us that the disease is unknown at Mount Aboo, and that it had never visited Otocamund prior to 1861. It is very difficult to account for the