GENERAL fONSIDEEATION OF DISEASE. 



49 



Hyphomycetes (Moulds). 



Hyphom3'cetes or moulds are non-chlorophyllic plants. Struc- 

 turally they are composed of mycelial threads from which up- 

 right reproductive organs may be formed. 'IMiey are usually 

 multicellular and reproduce by spores. They re(|uire preformed 

 foods and thrive best in the absence of light. 



Oospora porric/iucs (Achoriou Schoenleini) is the organism 

 that causes favus. These nrganisms have mycelia with h_\phae, 

 the latter may l)e branched and terminate in bulbous ends. The 

 mycelium is later con\'erted into oval spore-like bodies. Favus 

 is occasionally observed in dogs and cats, more rarely in horses 

 and fowls. The disease is characterized by dry scales which 

 are brown, yellow or e\'en white upon the surface and vary 

 from wdiite to sulphur vellow in their deeper layers. The areas 

 involved are usuallv not more than yi or ^4 inch in diameter, 

 and are usualh- devoid of hair. The lesion may occur on the 

 head, especiallv on the forehead, cheeks or ears, and on tlie 

 abdomen, or outer surface of the hind legs. 



SporotricJi'uuii Audouiiii (Trichophyton Tonsurans I is the 

 fungus that causes ring-worm (tinea tonsurans). This fungus is 



So-^^ 



. Trichophyton Xonsurane. showing myc-lium and spoil 



