578 MICROBIOLOGY OF THE DISEASES OF MAN AND ANIMALS. 



DERMATOMYCOSES.* 



The molds which cause skin diseases form a small group, with re- 

 lationships to the commoner forms of fungi very ill-defined. They pro- 

 duce a vegetative mycelium within the tissues of the host with fertile 

 branches which bear conidia but indicate little as to their group relation- 

 ships among fungi. Certain of these diseases have been carefully studied, 

 mostly from the pathological side. 



BARBER'S ITCH, RINGWORM, HERPES TONSURANS, TRICHOMYCOSIS. 

 The disease due to Trichophyton tonsurans (Fig. 97), Malm, has received 



FlG. 97. Trichophyton tonsurans. (After Hyde, from Adami and Nicholls.} 



many names in different languages. It attacks man and domestic animals, 

 the ox, horse, dog, cat, sheep, hog, probably other animals as well. It is 

 characterized by the formation of circular patches from which eventually 

 the hairs fall. These patches enlarge radially and fuse into large areas 

 covered with crusts with more or less discharge in the center. The 

 fungus is recognized microscopically by examination of hairs pulled from 

 the growing edge of the infection. The hyphae penetrate the layers of 

 the skin and especially surround the roots of the hairs which, when first 

 affected, stand stiff and straight. 



* Prepared by Charles Thorn. 



