Diseases of the Skin. 241 
of the skin, and appear to be due to some special form 
of local irritation. They are to’ be seen on the free 
edges of the ears, lips, and especially the eyelids; and 
in some animals the mucous membrane of the mouth 
and prepuce is a common location. Other parts of the 
skin are also liable to invasion, but probably not so 
frequently as those already named. The enlargements 
partake of a variety of forms. They are sometimes 
diffuse, or spread over the surface of the skin, at others 
they rise erect, and subsequently assume a spherical or 
other form, being very mobile, and united to the tissues 
of the true skin by a narrow cord-like neck. Their 
presence gives rise to various forms of inconvenience, 
such as friction against other objects, laceration, &c., 
and considerable irritation in old-standing cases by the 
cracking of the scales, and subsequent ulceration between 
them. : i. 
‘Treatment.—In the diffused variety the regular appli- 
cation of caustic, as the nitrate of silver, “or strong acetic 
acid, will be required. Those attached to the skin by a 
constriction or neck, are easily removed by ligature, 
torsion, or the écraseur. Early attention when the 
growths are small is likely to be of greatest service. 
Parasitic Diseases of the Skin,—The affections of 
this class are numerous and important. They arise from 
the irritation produced as the result of the efforts of the 
animal parasites in obtaining a nidus or hatching-place 
for their eggs. Some of these occupy their position for 
such a length of time when undisturbed as to indicate 
the permanence of their home; others are ephemeral in 
their visits, being endowed with organs of free loco- 
motion, as legs and wings of considerable power. In 
the first order we place the various forms of mange, or 
itch animalcules, and in the latter, fleas, ticks, lice, and 
other insects, amongst which the harvest bug is acommon 
example. In addition to these, we have also to notice 
another variety—viz., vegetable parasites, which likewise 
“prove exceedingly troublesome to canine animals, as 
well as disappointing to the hopes and aspirations of the 
owner. . 
16 
