ON THE VARIOLA OR SMALL-I’OX OF SHEEP. 625 
When once established in a district, it propagates itself from 
point to point with wonderful rapidity, inasmuch as animals under 
peculiar atmospheric influences are already predisposed to its 
reception. 
If a flock of diseased sheep have been folded upon a particular 
locality, or driven in a certain direction, and a healthy flock follows 
in the same line of district, the latter will immediately take it. The 
fever runs its course in from ten to fifteen days, according to cir- 
cumstances ; but it is often from three to four or five weeks before 
the animals clear thoroughly out of its effects ; and it is difficult to 
decide accurately at what precise period an infected animal would 
be incapable of propagating the disease, as it lurks so long amongst 
the wool. So infectious is it, that the shepherd, even his dog, 
the butchers and attendants, are capable of carrying the virus from 
flock to flock : even the transmission of the fleeces, the excrement, 
and whatever has been employed about them, will propagate the 
disease. 
One peculiarity belonging to the disease is, that it perhaps attacks 
capriciously only a third portion of a flock ; it then attacks another 
third, according to their susceptibility of the action of the poison ; 
the first section having it most severely, and by the period the last 
section has become infected (which may be from three to six 
months), the virulence of the morbific poison has become much 
milder. 
It may, like the small-pox in the human subject, be regular or 
irregular, mild or malignant. When the animal becomes infected, 
the disease is recognized by a dull anxious countenance, feeble- 
ness of gait, the head hanging down, the ears lowering, loss of 
appetite, rumination partially or wholly suspended, heat of skin, 
and frequent pulse, with acceleration of breathing. This state con- 
tinues three or four days, when an eruption develops itself on the 
more naked parts of the body, manifesting itself by small pustules 
of a red or violaceous colour, soon assuming the form of well-deve- 
loped pocks, white at the summit, insulated, or confluent (id est, 
running into one another), according to the mildness or malignity 
of the disease. The pocks have a well-defined border, being flat- 
tened in the centre, and of the size of a lentil. In favourable cases, 
as soon as the pustular eruption has maturated, the heat of the skin 
and the general febrile symptoms gradually subside, leaving no 
morbid effects behind. 
However, in more severe forms, the surface of the body is exqui- 
sitely sensitive and burning, the eyes become highly inflamed, the 
mouth is dry, great thirst, breathing accelerated and laborious, with 
rapid pulse. As the urgent symptoms increase, the breath becomes 
fetid, rumination ceases, the head swells, there is a discharge of 
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