INFLUENZA.. 
661 
and not making its appearance here in anything like a viru¬ 
lent form until we have the extensive outbreaks of 1870-71, 
when it spread over the entire country. 
It is to-day an almost permanent disease among the horses 
of our large cities, where bad ventilation and want of sanitary 
arrangements about the great majority of stables seem to 
keep the disease alive and perhaps predispose fresh animals to 
it. 
Influenza is a specific febrile disease, dependent upon a 
specific blood poison and prevailing as a epizootic. 
It is essentially characterized by a catarrh of the respira¬ 
tory and generally also of the digestive organs, by great and 
rapidly developed weakness, pains in the head and limbs, as 
well as by serious nervous symptoms and fever of greater* or 
less intensity. 
It is confounded generally with simple catarrh, but is dis¬ 
tinguished by its wide diffusion, its rapid spread and the num¬ 
ber of cases in the regions in which it occurs. 
We cannot lay its cause to atmospheric influences, as we 
have it occurring at all times of the year, during different 
climatic changes, and in countries whose atmospheric sur¬ 
roundings are totally different. 
We have it occurring at seasons of the year when climatic 
changes are such as do not produce catarrh, and aside from 
this we have those lesions of function, peculiar to influenza, 
that can in no way be connected with a simple catarrh. 
When we think of the numerous opportunities presented 
by this disease for investigation, and to what extent literature 
has been written upon it, we are surprised at what few facts 
have been gathered together concerning its cause and origin. 
A great many theories have been advanced as to the 
etiology of influenza, such as that of atmospheric influence; 
others give it a specific origin, but have never been able to 
isolate and demonstrate its specific cause; while on the other 
hand there are those who claim it has a spontaneity of origin, 
due to want of sanitation. This last is, I think, the weakest of 
all, as we have it occurring when sanitary arrangements are 
the best, as well as where they are almost entirely wanting. 
