778 MICROBIOLOGY OF DISEASES OF MAN AND DOMESTIC 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. 



The appearances of the disease differ in the various species of in- 

 fected animals, as also does the length of time it continues. The 

 disease does not affect the general health greatly, since it primarily 

 attacks the drier and more horn-like portions of the skin, but becomes 

 conspicuous by the falling of the hair and by the scabs or crusts with 

 accompanying itching and discomfort. Other species of the same genus 

 have been described which produce infected areas differing in detail 

 but similar in their general characters. 



FAVUS. Favus is caused by Achorion schonleinii, Remak, and 

 affects man, cats, dogs, mice, rabbits, and fowls, and many wild animals. 

 This is characterized by crusts, thickened at the edges and somewhat 

 cup-shaped in center, composed of the mycelium of the mold cemented 

 together into masses by glairy substance. Below, these crusts are in 

 contact with the true skin. The fungus penetrates especially into the 

 hair-follicles and hairs themselves, which later are shed. It attacks 

 different species of animals with varying symptoms, but produces more 

 serious lesions than those of Trichophyton. Favus is especially serious 

 as it attacks man. Efforts to show that this fungus is merely a parasitic 

 form of some species of higher fungi have failed. The diseased con- 

 ditions have become so well defined and are reproduced so uniformly 

 as to indicate a fixed habit in the organisms, whatever its source or 

 relationship. 



ACTINOMYCOSIS* 



Actinomyces boms] 



This is a rather common disease of domestic animals, especially 

 cattle. It prevails in Europe, North and South America, and is known 

 by various names as lumpy jaw and wooden tongue. Cattle are most 



* Prepared by M. H. Reynolds. 



f Actinomyces bovis has been classified by Frost (page in) as a species of bacteria, but. 

 yeaause of many features, it is here inserted with the organisms strictly belonging to molds and 

 yeasts. Ed. 



