190 



DISEASES OF POULTRY. 



falls into a decline which continues until the forces 

 of the body are exhausted and it dies. During the 

 course of the disease the affected birds give off a dis- 

 agreeable odor which has been likened by some to that 

 of moldy cheese and by others to the exhalations from 

 mice, cat's urine, or macerating animal substances. 



Causation. — Favus is a contagious disease, and, 

 as has already been stated, it is caused by a fungus 

 which has been named Achorion Schonleinii. If a 



small particle of one 

 *P of the crusts is taken, 



%0 .. .i>|t-i>' |\ placed upon a glass 



1 '« slip and moistened 

 with water or dilute 

 acetic acid and sub- 

 mitted to microscopic 

 examination at a 

 magnification of 300 

 to 500 diameters, it is 

 seen to be made up of 

 threads or mycelium 

 of tlie fungus held to - 

 gether by a thick, 

 viscid, gelatinous sub - 

 stance which it se- 



Frg-. 54.— The Achorion Srhovleiiiii of the 

 favus of poultry; mag-nified 800 diameters. CreteS. NumeroUS 



tv, empty tubes; tp, tubes filled with , 

 protoplasm and containing' spores; i, iso- Spherical O r OVoid 

 lated spores. 



Spores are also visible 

 both within the filaments and in a free condition. An 

 examination of the feathers on the affected parts re - 

 veals the fact that the fungus has penetrated the shaft, 

 filled it with crusts, and has in some cases even 

 reached the barbs. 



The disease may be inoculated from bird to bird. 



