435 
ravages by the disease in confined sheds. This is singular and not commonly 
known. ? 
Malady aggravated by turning cattle out.—It has been observed that a stock 
of cows, among which the disease had been lingering, may be rapidly thinned 
by deaths from the disease if turned out to grass in spring. Deaths have been 
more frequent and rapid when cows have been turned out for some hours daily 
and housed at night than when they have not been moved from their sheds. 
By free ventilation.—The disease having been introduced among stall-fed 
cattle kept in warm, and even ill-ventilated stables, the symptoms have been 
aggravated and deaths occurred much more rapidly after ventilating apertures 
have been made facing the heads of the cattle, and especially if such openings 
were made to the north and produced cold draughts through the stable. These 
facts have coustantly led to the confounding of contagious pleuro-pneumonia 
with colds and ordinary inflammations of the lungs. 
The disease transmitted by offal—The only circumstances under which I 
have known the lung disease to be communicated when there has been no imme- 
diate contact between living sick and healthy cattle has been on fields adjoining 
slaughter-houses, when cattle suffering from pleuro-pneumonia have been 
slaughtered. It is evident, however, that even in this case the sick cattle have 
breathed in the vicinity. 
How fur the virus may be carried in the air —We do not know how far the 
virus will be carried in the atmosphere. Usually the distance is very short. 
If a cow driven along a road communicates the disease, she does it by cattle 
approaching and drawing her breath as they rub their noses against each other. 
Influence of the introduction of steam in spreading the lung plague.—The 
history of the lung plague, which is dealt with in another section of this report, 
indicates that the introduction of steam has been a most active cause favoring 
the transmission of the malady. The wants of large cities,and the advance 
made towards annihilating distance as one of the impediments to the cattle traf- 
fic, have led to the dissemination of the disorder. 
Cities “ fixed stations” of the disease—In large towns, where cows are kept 
for dairy purposes, it is necessary that frequent purchases be made. ‘This tends 
to render cities “fixed stations” for the reproduction of the lung plague poison, 
and of these stations the most important and the oldest in America is that of 
Long island, in and around Brooklyn. 
Cattle.feeding districts liable—In Europe, those portions of countries where 
cattle are fed for the butcher and not bred—for instance, Fife in Scotland, Nor- 
folk in England, and Meath in Ireland—are, next to the large cities, ravaged 
by the disorder. : 
Breeding and exporting districts usually ecempt.—The breeding and export- 
ing districts, like ‘Texas and the western States of America, escape, except 
where blood-stock is introduced from infected countries to improve the breeds. 
The long period of incubation and the frequently latent cases of the disease 
explain its propagation from England or Holland to the United States, the 
Cape of Good Hope, and the Australian colonies. 
IV. SYMPTOMS OF THE LUNG PLAGUE. 
Premonitory symptoms in herds—When pleuro-pneumonia is introduced in 
a dairy or on a farm it is not unusual to,have newly-bought animals sickening 
and dying. At other times an ox or cow recently bought thrives, and an ex- 
pert auscultator is required to indicate that the animal is but recovering from 
the disease. 
Incubation of the disease-—Not uncommonly a herd thus contaminated re- 
mains healthy for six weeks or two months from the date of the last purchase. 
Often no indication of sickness is recognized by the farmer for as long as three 
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