562 THE PRACTICE OF VETERINARY MEDICINE. 



Those minute organisms known as animalcula? have come 

 in for their share of consideration, being firmly believed by 

 many to be the cause of this, as of some other diseases. 

 This is a very interesting theory, and one well worthy of 

 consideration, and by it certain of the symptoms can be 

 accounted for which hitherto could not be explained. Some 

 observers consider the disease to be due to microscopic 

 vegetable organisms, or cryptogama. This is the opinion 

 entertained by Mr. Moorhouse, of New York, who, on 

 examination of the discharge from the nostrils, found three 

 distinct species of vegetable organisms, all of them in a 

 vigorous state of development. According to the ' Veteri- 

 narian,' the observations of Mr. Moorhouse do not accord 

 with those of Prof. James Law, who subjected the particles 

 floating in the air from stables and fields to microscopic 

 examination both before and during the prevalence of the 

 epizootic of 1872, without discovering any important differ- 

 ence in the floating particles from first to last. 



This brings us to the much-mooted question of contagion 

 and infection. Most writers use these terms indis- 

 criminately, making no distinction whatever bet^veen them ; 

 still, I consider them as two different Avords, each with a mean- 

 ins: different to that of the other.- For instance, a contairious 

 ■disease may be defined as follows : A morbid condition of 

 the animal economy induced by the operation of a specific 

 poison, termed a virus or contagium, which, on being con- 

 veyed by actual contact into the system of a health}^ animal, 

 induces a condition identical with that of the body from 

 which it originated. 



An infectious disease is one w^hich has the power of 

 spreading itself by diffusion of the specific material through 

 the air. I am well aware that many eminent authorities 

 do not believe influenza to be either contagious or infectious, 

 and I cannot help experiencing a feeling of great diffidence 



