general health. The President held that for the present sanitary
procedure was independent of these theories on the germ origin in
particular of zymotic disease; but gave the facts as worthy of
consideration, as indicating points for the direction of those who aimed
at preventing disease.

The President dealt with the important subject of isolation in the cases
of contagious zymotic diseases, and then, proceeding to discuss the
subject of epidemic diseases, said: Notwithstanding the numerous
experiments and the great efforts which have been made in recent times
to endeavor to trace out the origin of disease, the sanitarian has not
yet been able to lift up the veil which conceals the causes connected
with the occurrence of epidemic diseases. These diseases come in
recurring periods, sometimes at longer, sometimes at shorter intervals.
Animals, as well as the human race, are similarly affected by these
diseases of periodical recurrence; but why they prevail more in one year
than in another we are entirely ignorant. They appear to be subject to
certain aerial or climatic conditions.

Cholera affords an illustration of this. There is a part of India,
low-lying, water-logged, near the mouth of the Ganges, where cholera may
be said to be endemic. In certain years, but why we know not, it spreads
out of this district, and moves westward over the country; the people
are sedentary, and seldom leave home, but the cholera travels on. At
last it arrives on the borders of the desert, where there are no people,
and no intercourse, no alvine secretions, and no sewers, yet the
statistician sitting in Calcutta can tell almost the day on which the
epidemic influence will have crossed the desert. But it exercises
discrimination in its attacks, It will visit one town or village and
leave many others in the vicinity untouched. Similarly it will attack