650 



RINGWORM. 



neigbourhood of the lips, the nostrils and sub-maxillai7 region, as 

 well as the throat and neck. It assumes the form of circular 

 patches, over which the hair stands erect. 



Gruby in 1842 discovered the parasite of tinea tonsurans, or 

 herpes, and thus proved that the cutaneous lesions were not due to 

 any constitutional condition, as was long thought, although dirt, bad 

 hygienic conditions, and crowded stables favoured the spread of ring- 

 worm. 



Direct contact between healthy and diseased animals and the 

 transport of spores, by combs, brushes, etc., favour contagion. The 

 disease may not only be conveyed from one animal to another of the 



same species, but from the ox to 

 man, and, with somewhat greater 

 difficulty, from the ox to the horse. 

 Cases of transmission from the ox 

 to the sheep, pig, and dog have 

 also been recorded. 



Megnin in 1890 attempted to 

 prove that all the trichophytons pro- 

 ducing ringworm in animals do not 

 belong to the same species, and gave 

 the name of Tricliophyton epilans to 

 that usually found in the ox, be- 

 cause it causes absolute loss of the 

 hair by growing in the follicle, whilst 

 he named the parasite found in the 

 horse Trichophyton tonsurans, be- 

 cause it only grows on the surface 

 of the skin and in the thickness 

 of the hair, without causing inflammation of the hair follicle and 

 without invading it. 



The epidermis soon undergoes proliferation, and becomes covered 

 with crusts, which adhere to the hairs, gluing them together, and 

 finally causing them to be shed, leaving bare patches the size of a 

 shilling or a florin. The lesion extends in an ever- widening circle, 

 until it attains, perhaps, the dimensions of a tive-shilling piece or 

 more. 



The affected hairs break off level with the free surface of the 

 skin, rendering the patches more apparent. White hairs are less 

 affected, and some always remain projecting above the crusts, causing 

 the patches, when on a white skin, to retain a certain amount of 

 covering. 



At first the crust is closely adherent to the skin, and, if forcibly 



Fig. 266.— Calf suffering from 

 ringworm. 



