ECZEMA IMPETIGINODES. 



677 



orifice. Professor Heriug lias found in chronic grease large 

 nunibers of acari, called sarcoptes hippopodus, of which the 

 accompanying woodcut (Fig. 117) is an illustration. 



Hering says of it that its body is twice as long as broad, 



beset all over with hairs like satin ; head retractile ; proboscis 



consisting of two valves moving laterally ; mouth directed rather 



downwards ; close to it two small palpi ; eight feet, five-jointed, 



the last joint as long as the four 



preceding, with a small sucking disc 



at the end, and two small hairs on 



each joint. Two pairs of feet originate 



near the head, and two posteriorly on 



the belly. On the abdomen a small 



prominence, and four long, straight, 



plumose bristles; their length 016. 



their breadth 0-08— 0-085"'. The 



three pairs of bristles on the back 



and those at the abdomen can be 



raised like the tail of a peacock. The 



large bristles are plumose ; the hairs 



1 i ^ \ \\''^ "* *-'^^ ^^^® joints of the feet diminish in 



/I ( \\ h length towards the extremity of the 



foot. Only the third joint of the 



first pair of feet has a longer hair. 



The presence of this parasite in 

 chronic grease is accidental; and 

 other diseases, such as canker, mal- 

 lenders, and sallenders, are apt to 

 become complicated with a mange' caused by this parasite. 

 Gerlach designates this epizoon syvibioUs cqui, and says that the 

 disease induced by it may be called foot-mange; but it has 

 nothing in common with canker, or other known cutaneous 

 eruption. Attention is at first drawn to a horse with this 

 disease by his rubbing his fore legs, or striking constantly with 

 the hind ones during the night. The seat of the disease, and 

 the ready detection of numerous parasites in clusters where the 

 crusts or scabs form, about the horse's heels, &c., sufl&ce to enable 

 us to diagnose the malady. 



The swelhng of the legs affected with grease, at first consisting 

 of material capable of reabsorption, becomes transformed, in 



Fig. 117. — Sarcoptes hippopo- 

 dus.— (HERmG.) 



