AVIAN TUBERCULOSIS 185 
diameter. In advanced cases they are larger. They have a cheesy 
consistency, and are easily removed from the surroun ding tissue. The 
removed, necrotic nodules have a roughened surface. The color 
is greyish or whitish in the early stages, but in the later ones it changes 
to a yellowish tint. Occasionally there are two distinct crops of 
tubercles, one consisting of nodules 4 to 6 millimeters in diameter and 
separated by a centimeter or more, and the other of closely set grayish 
Fig. 44. A PHOTOGRAPH OF A SECTION OF TUBERCLE FROM 
A FOWL, SHOWING THE NECROTIC CENTER AND 
SURROUNDING ZONES. ENLARGED. 
tubercles 0.25 to 0.5 mm. in diameter. In some cases the tubercles 
are few in number but larger in size. The liver cells between the 
tubercles are usually in a state of more or less degeneration, and 
frequently fat globules are numerous. The blood spaces are more 
than normally distended with blood. The lesions in the spleen, like 
those in the liver, consist of minute or larger tubercles of a grayish or 
of a yellowish tint. The central portions of the larger tubercles are 
often homogeneous, darker in color and more or less hyaline in appear- 
ance and consistency. 
The tubercular growths in the intestine start in the walls of the 
intestine. They present a glistening appearance, grayish in color 
