Diseases of the Liver 97 



The amoeba leaves the bodies of the sick birds with the 

 excrement and infects other birds by entering the digestive 

 organs with the food and drink. It passes along the ali- 

 mentary canal until it arrives at the two blind pouches or 

 lateral extensions called the ceca (Fig. 7), where it begins its 

 growth and produces the first signs of disease. Here it 

 penetrates the lining membrane, increases rapidly in num- 

 bers, and sets up an inflammatory process which leads to 

 a great thickening of the intestinal wall and to the filling 

 up and obstruction of the tube with an accumulation of 

 yellowish white or grayish cheesy material that is deposited 

 in concentric layers. 



The changes which are almost constantly found in the 

 liver are explained by assuming that the microbes are 

 carried by the blood from the diseased ceca to the liver, 

 and are there deposited at different points, where they 

 multiply and spread in all directions. In this way are 

 formed the numerous centers of disease which appear on the 

 surface of the liver as yellowish spots, but which when cut 

 across are seen to be irregularly spherical in shape. The 

 amoebae are liberated in large numbers both in the ceca and 

 in the liver, are mixed with the intestinal contents, and are 

 distributed with the droppings. 



There is some difference of opinion as to whether the 

 amoeba is ever present within the egg of diseased turkeys, 

 but the indications are that the infection is not carried in 

 this way. It no doubt often exists on the outside of the 

 shell, from contamination when the egg passes through the 

 cloaca, and for this reason the eggs should be carefully 

 cleaned before they are put under the sitting hen or into 

 an incubator. 



An important recent conclusion is that common fowls 

 harbor this parasite, although they rarely suffer sufficiently 

 from its attacks to show marked symptoms of disease. They 



