CHAPTER III. 

 RINGWORM, 



The old term " ringworm " is still used to indicate a well-marked 

 skin disease due to parasitic fungi which grow at the expense of the 

 epidermis. Other names, such as dermatophytis and epidermophytis, 

 have heen suggested, to indicate the mode in which the parasite 

 grows. The term dermatomycosis suggests a cutaneous vegetable 

 parasite. 



The dermatomycoses of the domestic animals are caused by fungi 

 belonging to six distinct genera : — 



Trichophyton (horse, ass, ox, dog, pig) ; Eidamella (dog) ; Micro- 

 sporum (horse, dog) ; Achorion (dog) ; Lophophyton (fowl) ; Oospora 

 (dog). 



Kingworm is common in animals of the bovine species, but very 

 rare in other domesticated animals, except, perhaps, the horse. It 

 is caused by the growth of a parasite, Trichophyton mentagrophytes 

 (Eobin), of the genus Trichophyton, family Gymnoascea, order Asco- 

 mycetes. 



The ascosporaceous form of reproduction is still unknown, but the 

 mode of reproduction by conidia is characteristic. In cultures the 

 mycelium is represented by growing filaments branching off at right 

 angles, and by separate superficial aerial reproductive filaments of 

 the conidian form. There is some reason for believing that these 

 fungi may lead a saprophytic as well as a parasitic existence, i.e., 

 that they can exist and multiply apart from the animal body. 



Their vitality is marked. Various experimenters have transmitted 

 the disease with crusts kept for eighteen months. Thin declares 

 that in two and a half years the spores had lost all power of germi- 

 nation. They resisted immersion in water for two days, but were 

 dead after eight days. Soft soap and 1 per cent, acetic acid kill 

 them in an hour. 



Symptoms. The disease most frequently attacks young animals 

 and milch cows — very rarely adults or old animals. This peculiarity 

 is very difficult to explain. 



In calves, ringworm seems specially to attack the head, the 



