ORDER ACARINA: THE MITES 289 



and are set free by the normal process of proliferation and 

 desquamation of the epidermis. Pairing occurs while the 

 female is still in the nymph stage, and when the fertilised 

 nymph has become adult she starts a burrow of her own. 

 The irritation caused by the mites leads to scratching, such 

 as Thersites desired for Ajax, which increases the eczema 

 and also spreads the infection. The severity of the inflam- 

 mation depends upon its duration and on the habits of the 

 patient — whether cleanly or not. In a mild attack that is 

 attended to at once, there will only be a few small vesicles or 

 -pustules on the back of the hand, near the finger-clefts ; in a 

 neglected case in a dirty person all parts except the head and 

 face may be affected. The parasite seems to spread from 

 one individual to another solely by contact. Treatment 

 consists in the free use of soap and hot water and the liberal 

 application of sulphur ointment, continued for several days. 

 Some prefer baths of potassa sulphurata (i oz. of the salt 

 to 4 gallons of water). Clothing and bedding should be 

 fumigated with sulphur, and baked. There are other species 

 of Sarcoptes that attack domestic animals. 



The genus Psoroptes is distinguished from Sarcoptes by 

 having the stalk of the suckers segmented, and the chelicerae 

 non-chelate. One species is a notorious cause of scab in sheep. 



The genus Chorioptes includes several species that attack 

 farm-animals and cause mange and scab. In this genus the 

 body is not so squat as in Sarcoptes, the male has the third 

 pair of legs very much larger than the fourth, and the female 

 has suckers on the fourth pair of legs. 



The species of Otodectes live in the ears of dogs and cats, 

 and may cause much suffering. The legs in this genus are 

 slenderer than in Sarcoptes, and in the male the third pair 

 are much larger than the fourth. 



Cnemidocoptes is parasitic on birds, the species attacking 

 and loosening sometimes the feathers sometimes the scales 

 of the legs. The females are distinguished from those of 

 other itch-mites by not having a sucker at the end of any of 

 the legs. 



The treatment of all these parasitic skin affections of 

 domestic animals is in principle the same as that of itch in 

 man — lotions and dips of potassa sulphurata, or of sulphur 



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