696 



DISEASES OF THE SKIN". 



SCAB IN SHEEP. 



Three forms of scab are described, viz., the sarcoptic, derinato- 

 dectic, and symbiotic. The dermatodectic or psoroptic is the 

 common form known in this country ; it is intensely contagious, 



Fig. 125.— Dermatodectes ovis, — (Gerlach.) 



and spreads with great rapidity, the parasite wliich causes it 



