88 



POULTRY DISEASES 



year, altlioiigli I liave seen the disease in birds that 

 were iinK']i older. Several outbreaks have been 

 studied in this laboratory. Only one case was 

 found in the lien. It has been reported in the pea- 

 cock. 



Fig, 29. Section of the Liver (from a Case of Blackhead) 

 a. Protozoa causing the disease, b, a giant cell. 



The symptoms are not manifest till the disease 

 has progressed to a considerable extent. The bird 

 is first noticed to be dull, later the wings and tail 

 may droop; the feathers become ruffled and the 

 bird sits around much of the time ; diarrhea super- 

 venes, the discharge being of a greenish-yellow 



