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YORKSHIRE VETERINARY MEDICAL SOCIETY. 
swollen, with great tenderness in them. This type of disease may 
continue six or twelve months, subside we know not how, or why, 
and we may have again a long period of absence of cases of an 
epizootic kind, when all at once we have numbers of cases with 
sore throat and profuse discharge from the nostrils; some of the 
worst kind have a straw-colour or yellow discharge. This form is 
sometimes called epidemic catarrh ; we may have a run of this for 
several months, and it, like its predecessors, will subside without 
any evident or definite reason. Again we may be comparatively 
free for a time, when all at once there will occur one and then another, 
and then a run of cases in which the organs of respiration are chiefly 
affected by a low inflammation, constituting what is sometimes called 
chest influenza. This last is by far the most serious type of the 
epizootic, and requires the deepest and most attentive considera¬ 
tion ; these cases progress insidiously. At length the disease 
subsides, like its predecessors, we know not how or why; but, as in 
the previous visitations, it would appear that the cause, whatever it 
may have been, had become less and less virulent, and had in the 
end entirely expended itself; in fact, the history of every epizootic 
and every epidemic they have their entrances and their exits in a 
similar way. The fact of a disease existing in particular localities 
is not certain proof of its being either infectious or contagious; 
these terms seem not to be rightly understood by most persons. 
The spread of disease is often a result of some local causes wholly 
apart from and independent of infection.' 
From researches of eminent men, such as Professor Huxley, 
Professor Tyndal, Dr. Angus Smith, and others, who have given 
much time and close attention to the subject, we have scientific 
knowledge developed and placed in our possession in advance of 
anything known before on the theory of germs, dust particles, and 
fungi existing in the atmosphere, and their power in producing 
disease ; they have shown that the germs or fungi in which the virus 
of cholera and cattle plague is known to exist, acquire at times, as do 
the germs of other contagious diseases, an unusual power of repro¬ 
duction ; that such germs may be carried by man, or animals, or 
goods, or ships, or be scattered by wind to regerminate wherever 
specially favorable conditions are found. 
Professor Simonds said that the infection of cattle plague was so 
virulent that if only a small quantity of the excreta of a diseased 
cow were carried on the point of a lancet from one end of England 
to the other, it would be quite sufficient to infect a whole herd ; 
and further, that the laws on which infection depended were as 
inevitable and as incapable of change as were the laws that governed 
the universe. 
Professor Tyndal has demonstrated that the germs (and germs 
are seeds or ova of living organisms) which are floating in the 
atmosphere can enter the system, and growing there produce 
various disorders ; he has shown that in ordinary atmosphere in a dry 
room in which a fire or gas is burning, the particles floating in the 
air consist of fragments of coal, granite, vegetable, hairs, cotton 
