692 ON MURRAIN, OR THE VESICULAR EPIZOOTIC. 
brane (the mucous lining of the mouth) is thickened, exhibits 
little reddish elevations, and, in about twenty-four hours from the 
first appearance of the disease, is raised into blisters extending 
across the upper part of the mouth, along the sides of the tongue, 
within the lips, on the muzzle, and in the nostrils. In some cases 
vesicles have been observed around the roots of the horns. The 
eruption of these vesicles is generally attended by a diminution of 
the febrile symptoms, and the animal appears more easy. The 
vesicles are generally largest and most abundant along the roof of 
the mouth. They are irregular, with undulating edges, and without 
any central depression. They are not surrounded by the distinct 
zone or areola, which is observable in the pustule of cow-pox. 
Their margins seldom shew any redness or inflammation, nor is 
there tumefaction of the neighbouring parts. They are at first 
about the size of a millet seed, but gradually become as large as a 
kidney bean, and in some cases considerably larger. Their epi- 
thelial (cuticular) covering is white. The serum contained is at 
first clear, but after some hours becomes opaque. This opacity 
results from the mixture of epithelial scales, shreds of lymph and 
exudation corpuscules. In some cases the fluid contained in these 
vesicles is reabsorbed, and desquamation (separation of the cuticle) 
follows. The scales formed are very thin and easily peeled off, a 
red raw surface becoming exposed. Sometimes the vesicles burst, 
and scabs are formed. Some few of the severer cases run on to 
ulceration. These ulcers are of a greyish white appearance, are 
quite superficial, and covered by a glairy mucus which hardens 
over them. In favourable cases their edges quickly approach ; 
the matter they secrete becomes whiter and less abundant, and a 
cicatrix is formed in from eight to ten days from the first attack. 
But the eruption is not confined to the mouth and the conti- 
guous parts. Vesicles also appear in the interdigital spaces, and 
sometimes upon the udder and external organs of generation. The 
hoofs are separated, and seem very small from the increased size of 
the parts above them. The feet are hot and painful, and blisters 
extend between the digits to the upper and back part of the heels. 
From inattention to cleanliness, suppuration often ensues; and the 
severer cases sometimes run on to caries of the bones, and ulcera- 
tion and sloughing of the cartilages, ligaments, and synovial bursae. 
(The synovial bursae contain the fluid which lubricates the inner 
surface of joints). The hind feet are more frequently affected 
than the fore feet. This is especially the case in stall-tied animals, 
and appears to result from the hind extremities being more ex- 
posed to wet and dirt. In cases in which the vesicles in and 
about the mouth are large and numerous, the feet suffer less 
severely ; but if, on the other hand, the feet are the chief seat of 
