SKIN DISEASES. 275 



PARASITIC DISEASES OF THE Sk'IX. 

 COMMON RINGWORM. TINEA TONSURANS. 



This is common in horses, cattle, dogs, and cats, as well as 

 in man, and is readily transmitted from one to the other. It 

 is especially common in winter or spring, and occurs as round 

 bald spots on the face or elsewhere, covered with white scales, 

 and surrounded by a ring of bristly, broken hairs, or split 

 hairs with scabs around the roots and some eruption on the 

 skin. Soon this ring of broken hairs is shed and a wider bristly 

 ring is formed. Among the naked eye characters the breaking 

 and splitting of hairs in the ring, and the perfect baldness of the 



Fig. 42. — Hairs with spores of Trichophyton Tonsurans. 

 From the Horse. — Megni'n. 



central part are the most significant. Chloroform bleaches the 

 affected hairs, while the sound ones are unaffected. The 

 microscopic appearances are the presence in the hairs and hair 

 follicles of a vegetable parasite {Trichophyton tonsurans). 



Treatment. — Shave the hairs from the affected part, or better 

 pull them out with a pair of pincers, and paint with tincture of 

 iodine, or a solution of corrosive sublimate (40 grains to i pt. 

 of water), or of bisulphite of soda {h oz. to i pt.). 



HONEYCOMB RINGWORM. FAVUS. 



Common in cattle, dogs, cats, rabbits, and chickens, as well as 

 in children (scald-head). It shows the same general appearance 

 of baldness advancing from a centre, which is described above, 

 but a cup-shaped yellowish scab results, which has obtained for 

 it the name. The parasite (Achorion Schurdeini) appears to be 



