130 DISEASES OF POULTRY. 



organs in the bird's body. It not only prepares the 

 bile, which is one of the principal digestive liquids, 

 but it assists in some of the most necessary chemical 

 changes which occur in the blood. This organ con- 

 tains numerous blood vessels through which passes a 

 very large quantity of blood, and it is particularly 

 subject to the attacks of various kinds of parasites. 

 Most of these parasites probably find their way to the 

 liver through the blood channels, lodge in the minute 

 capillary vessels, and begin their multiplication and 

 disease -producing action. 



Among the parasites which most frequently afiect 

 the liver of fowls are the chicken cholera bacteria, the 

 tubercle bacillus, the protozoa of black-head (tur- 

 keys), and the aspergillosis fungus. These variously 

 cause congestion, inflammation, and death of the tis- 

 sue. 



The liver is very subject to congestion and this fre- 

 quently occurs from errors in feeding and as a result 

 of irritation in the neighboring intestines ; it is, also, 

 frequently affected with atrophy and fatty degenera- 

 tion. 



CONGESTION OF THE LIVER. 



The liver of fowls is often found in a congested con- 

 dition as the result of lack of exercise combined with 

 over-feeding; also from the birds taking tainted or 

 moldy food or poisonous substances of various kinds 

 into their digestive organs ; from the effects of infec - 

 tious diseases, particularly cholera ; and from obstruc- 

 tion to the circulation of blood by disease of the heart 

 or lungs. It is often seen in birds which are in pleth- 

 oric condition or very fat. 



The symptoms are obscure and it is difficult to- 

 make a diagnosis during the life of the affected bird. 



