ON THE NOSOLOGY OF PLEUROPNEUMONIA. 475 
exercise his art] Yet such is the course daily adopted in this 
cattle epidemic. 
Our ancestors knew better: they gave these epidemical dis- 
orders, putting on different shapes, the generic term of “ murrain.” 
At a later period we find the terms “influenza,” “epidemic fever,” 
or “ distemper.” These terms were merely used to designate a 
generally prevalent disorder, having many characters in common, 
and existing only during a certain length of time. Of the different 
terms which have at various times been employed, the one of all 
others the most correct is that of “ epidemic fever.” It at once 
conveys an idea of the existence of a disease of a peculiar charac- 
ter, different from those that ordinarily occur. 
Another point must not on any account be lost sight of in the 
consideration of these epidemics. They are one and all referrible 
to the class of fever in some one or other of its forms. Another 
point of importance is the law of nature, that no two diseases of a 
violent kind can exist at one and the same time in the same body. 
Therefore it follows, that, when this disease is more particularly 
situated in one organ, it is nearly or entirely confined to that organ. 
It may be generally diffused over the whole system, and so remain 
until some peculiar, accidental, or exciting cause, occasions it to 
become concentrated on one particular part. A general derange- 
ment of the whole animal economy will always be found to pre- 
cede the concentration upon any one part. It may be, however, 
so slight as to escape the notice of the attendant, or it may be of 
so short a duration as to pass by unheeded. It will, therefore, ap- 
pear to common observers, that a disease starts at once from appa- 
rent health into activity at a single bound. A careful observer 
would, however, be often able to detect latent symptoms of mis- 
chief for days previous to the direct attack ; nay, in some instances 
it may be detectible for weeks, yet, during this time, the animals 
appear to be performing all their functions in a healthy manner. It. 
is difficult to convey a knowledge of these minute points. It can 
only be obtained by careful observation based on true principles, 
combined with a correct knowledge of physiology and pathology. 
If our veterinarians would only turn their attention to these mat- 
ters, and steadily prosecute their investigation, the subject now so 
difficult to be understood would be rendered clear, and the vast 
amount of crudities and nonsense now so current would be dissi- 
pated. 
It is not intended in this communication to enter into the con- 
sideration of the disease itself. The object is to shew the import- 
ance of clearly defining the meaning of general terms, in order that 
all may properly understand them. 
I am, Sir, your obedient servant, 
Wm. Arthur Cherry. 
