Yellow Fever is confined strictly within a certain geographical range, and limited by the atmospheric temperature of the climate and season; too great, as well as too low a degree of heat appearing to be alike inimical to its production. It is invariably arrested by the appearance of frost.

The natives and permanent residents of the localities to which the disease is natural, are in a great measure exempt from its attacks, as is also the negro race.

Persons who have once suffered an attack of the fever are generally, though not invariably, exempt from a recurrence of the disease in future.

The native habitations of the Yellow Fever are on the shores and islands of the Atlantic Ocean, or the Mexican Gulf, or the western part of the Mediterranean Sea, or on great rivers emptying into one or other part of those waters.

The germs of the Yellow Fever poison can live and multiply only during continuous warm weather (average of 80 Farenheit for a month,) with a high dew point, that is, an excess of moisture in the atmosphere. They require also for their development abundant products of vegetable and animal decay, especially the former. Yellow Fever is a disease, not of the country, nor of inland towns, but of sea-ports, or cities on great rivers near the sea; occasionally only among rural settlements or plantations.

As Canada is beyond the Yellow Fever bounds, and as copies of this work are not likely to find their way into a Yellow Fever country, it is not worth while to occupy space with a long description of the fever and its treatment.