26 Veterinary Medicine. 



comparative absence of protoplasm in the mycelia and their 

 greater tendency to branching. The cupped aspect of the crust, 

 and the presence of a homogeneous, agglutinating viscid material 

 full of moving granules and rods between the more solid elements 

 (spores and filaments) add to the clearness of the distinction. 

 The microscopic examination for these elements is essentially the 

 same as for the trichophyton. 



Accessory Causes. These are the same as in circinate ring- 

 worm, being such as favor contact or the preservation and dif- 

 fusion of the spore. Debility favors as in the nine-year-old bitch 

 of Trasbot, exhausted by gestation and nursing. Skin abrasions 

 furnish excellent ground for colonization. 



Animals Susceptible. It is common on mouse, rat, cat, dog, 

 rabbit, guineapig, and it is alleged by Neumann the chicken and 

 pigeon. Zurn, Megnin, W. Williams, Bassi, Friedberger and 

 Froner describe favus in the horse ; Williams and Girard in cat- 

 tle, and Kowalewsky in the sheep, yet Neumann doubts the diag- 

 nosis. Children often acquire it from the cat, which, in its turn, 

 received it from the rats and mice. Early youth is a strongly 

 predisposing element, but age gives no guarantee against its 

 ravages. 



Development of Crust. According to Bazin and others the 

 fungus is planted at the opening of the hair follicle and pene- 

 trates to the mucous layer between the epidermic layer and the 

 true skin. As it multiplies and expands it rises all around, 

 while the centre is held down by the connection of the epidermic 

 cells with the surface of the hair. The cryptogam further invades 

 the hair, directly (Unna) or by extending to its papilla and grow- 

 ing into its softer bulb (Kaposa, Balzer). 



Symptoms. Cat. The disease being derived mostly from 

 its prey (rats, mice), it attacks by preference the paws, lips, face, 

 and, in the young, the umbilicus. The latter is infected by the 

 lips and tongue of the mother. Once established at any point it 

 is liable to be speedily implanted on any other through scratching 

 and licking. The crusts of a sulphur yellow when recent, or 

 grayish when older, range in size from a mere point to a scaly 

 cupshaped mass of 4 mm. in diameter, round or more or less in- 

 dented at different points on the margin , and often becoming con- 

 fluent so as to form extended patches. The central cupping, 



