50 INFLUENZA. 



indirectly, tend to induce influenza : these are the influences 

 or agencies meteorological and telluric. Probabl}'- less in our 

 day than in previous periods, when the causes of epidemic and 

 epizootic diseases were more matters of speculation and imagina- 

 tion, and not as now subjects of experimental inquiry, and to 

 be demonstrated and made patent to the senses by the evidence 

 of fact and observation, is this class of agencies viewed with 

 favour and accepted as sufficient to explain the appearance of 

 these diseases. It is found to prevail under the most opposite 

 of atmospheric conditions of heat and cold, dryness and 

 moisture, high and low barometric pressure, and of varying 

 and opposite electrical conditions. Neither in its distribution 

 does it seem influenced by geological formations nor varying 

 conditions of soil or cultivation, and as little by astronomical 

 influences or terrestrial movements. 



It has been said, and with much truth, by Professor J. Law, 

 in his article on ' The Horse-Disease ' in America, that ' Much 

 of the confusion in which the subject of causation is involved 

 would be cleared away could we decide as to whether the 

 disease is contagious. In other words, if the introduction of a 

 sick animal into a healthy district well out of the former area 

 of the disease lead to a speedy diffusion of the malady in this 

 new locality, we must conclude that there exists a sj^ecific 

 poison capable of being carried in the diseased body, and pro- 

 bably capable of increasing indefinitely there. ... If these 

 conditions can be brought into extensive operation in a new 

 locality by the mere arrival of a sick or infected animal — if it 

 can be shown that the malady is communicated from one 

 animal to another — and that it Avill spread rapidly in a new 

 locality from a ncAvly imported sick animal as a centre — we 

 can only conclude that the malady is caused by a specific 

 poison, of which the diseased system is at once the storehouse 

 and the field for its fertile reproduction.' — Tlte Veteri- 

 narian, 1873. 



There is little doubt that both the contagious and non-con- 

 tagious views of the origin and propagation of influenza in the 

 horse may be supported by evidence which is often very diffi- 

 cult, if not impossible, to controvert. It seems to appear 

 amongst a number of horses previously healthy, and where, as 

 far as we are able to discover, no contact, cither by direct or 



