CHAPTER XLIIL 



DISEASES OF THE SKIN — continued. 



SCABIES — DIFFERENT VARIETIES OF ACARI SARCOPTES DERMATO- 



DEOTES — SYMBIOTES — CLASSIFICATION EXPERIMENTS OF HERING, 



HERTWIG, AND OTHERS AS TO THE TRANSMISSIBILITY OF THE 



MITES TO MAN MANGE IN THE HORSE AND OX — SCAB IN SHEEP 



MANGE IN THE DOG AND CAT TREATMENT OF MANGE — 



DISEASES DUE TO EPIZOA POULTRY LOUSINESS FLEAS — TICKS 



BOTS MAGGOTS. 



PARASITIC DISEASES OF THE SKIJT. 



This order of skin diseases may be considered under two 

 heads : — (1.) Diseases due to the presence of parasites from the 

 animal kingdom (dermatozoa) ; and (2.) those due to parasites 

 from the vegetable kingdom (dermatopliyta). 



I. DISEASES DUE TO ANBIAL PARASITES. 

 SCABIES. 



Scabies, mange, itch, or scab, is a contagious skin disease, 

 due to the presence of animal parasites belonging to the class 

 araclmida, the order acarida, or mites ; sub-order, crawling 

 mites; family, sar copies, of which there are, according to Gerlach, 

 three genera : — a, sarcoptes, that burrow in the skin; h, dermato- 

 dectes,that simply bite and hold on to the skin; and c, symbiotes, 

 living together in large numbers, and piercing no farther than 

 the epidermis in search of food. 



All these parasites live on serosity, the effusion of which is 

 caused by the irritation wiiich they excite. 



