712 



DISEASES OF THE SKI^T. 



propagating most rapidly, as the following table furnished by 

 Geiiach will show : — 



Its first symptom is itchiness, attempts to allay wdiich soon 

 give the animal a ragged appearance, tufts of wool being pulled 

 out, leaving white patches. If the animal be caught and the bare 

 parts examined, a slightly prominent pimple of a yellowish red 

 colour will be observed. Upon the surface of this pimple a small 

 blister or vesicle soon forms, its contained serosity, being dis- 

 charged, forms the crust or scab, and at a little distance the 

 parasite may be discovered amongst the wool. If the bare 

 patches be gently rubbed or scratched, the sheep will express 

 its pleasure by rapid movement of the lips or smacking. 



The parts first attacked are the back, sides, and shoulders, 

 and but very rarely the lower parts of the body and limbs. 



The vesicles soon become confluent and sometimes pustular, 

 the wool is easily detached along with the crusts, and the under- 

 lying skin is thickened, wrinkled, inflamed, and scaly. 



The sarcoptic variety was discovered in 1838 by Delafond, the 

 parasite being analogous to the acarus of the human species. 



According to Mr. Fleming, " its first indications are observed 

 on the upper lip around the nostril, and rarely on the eyelids 

 and round the ears, by its appearing as a weU-defined vesicle 

 with' a red areola. Very intense pruritis causes the animal to 

 lick the lip, rub the parts against any object it can find, or 

 scratch them with its hind or fore feet. The vesicle is in this 

 way ruptured, the yellowish serosity it contains escapes, and 

 forms a round hard crust. Analogous papulae and vesicles appear 

 on the limbs which have been employed in rubbing the lip and 

 nose ; and these parts are soon covered with dense greyish 

 crusts, beneath wJiich the sarcoptes congregate. At a later 

 period the disease invades the whole of the face, cheeks, eyelids, 

 and the lower portion of the limbs ; though, strange to say, it 

 does not attack those parts of the body covered with wool. The 

 diseased patches extend and become more numerous and co- 



