DISEASES OF POULTRY. 



107 



Figf. 20. — Liver of diseased turkey. 



ance and is flattened or even slightly depressed below 

 the surface. The liver may have few or many of these 

 centers of disease, which when cut across are found to 

 be deeply imbedded in the tissue of the organ and to 

 have in general a spherical form. Occasionally the 

 lesions are very extensive and the death of large por- 

 tions of the liver tissue follows. 



Causation. — The disease is caused by one of the 

 protozoa, which Smith has named the Amoeba melea- 

 gridis. This parasite is taken into the digestive or- 

 gans with the food or drink, it attacks the mucous 

 membrane of the caeca, causing the development of in- 

 flammation and leading to the changes already describ - 

 ed. The affection of the caecum is due primarily to 

 the multiplication of the micro-organism, which takes 



