XXIX-XXXII.]

_Definition and history._--This disease has been eradicated from the United
States, and it is not probable that it will ever be seen in this country
again. As, however, much interest was manifested in regard to it for a
number of years, and as our cattle are still prohibited from some foreign
markets on account of its previous existence here, the subject is treated
at greater length than would otherwise be necessary.

The contagious pleuropneumonia of cattle is a specific, epizootic disease
which affects bovine animals, and from which other species are exempt. It
is characterized, when the disease results from exposure in the usual
manner, by an inflammation of the lungs and pleurae, which is generally
extensive, and which has a tendency to invade portions of these organs not
primarily affected and to cause death of the diseased portion of the lung.
This disease is frequently called the lung plague, which corresponds to its
German name of Lungenseuche. In French it is spoken of as the peripneumonie
contagieuse.

The history of the contagious pleuropneumonia of cattle can not be traced
with any certainty to a period earlier than the beginning of the eighteenth
century. No doubt it existed and ravaged the herds of Europe for many years
and perhaps centuries before that time, but veterinary knowledge was so
limited that the descriptions of the symptoms and post-mortem appearance
are too vague and too limited to admit of the identification of the
maladies to which they refer. It has been supposed by some writers that
certain passages in the writings of Aristotle, Livy, and Virgil show the
existence of pleuropneumonia at the time that their works were composed,
but their references are too indefinite to be seriously accepted as
indicating this rather than some other disease.

It seems quite plain that as early as 1713 and 1714 pleuropneumonia existed
in Swabia and several Cantons of Switzerland. There are even clearer
accounts of its prevalence in Switzerland in 1732, 1743, and 1765. In 1769
a disease called murie was investigated in Franche-Comte by Bourgelat which
undoubtedly was identical with the pleuropneumonia of to-day. From that
period we have frequent and well-authenticated accounts of its existence in
various parts of Europe. During the period from 1790 to 1812 it was spread
throughout a large portion of the Continent of Europe by the cattle driven
for the subsistence of the armies, which marched an