MORBID ANATOMY 209 



2 to 5 mm. in length. On section the young tubercles exhibit 

 a grayish, glistening surface, but the more advanced nodules 

 contain recognizable necrotic centers. In the larger tubercles 

 on the intestines the necrotic centers frequently open into 



the lumen. 



Tlie skin lesions consist of a cellular infiltration usually 

 about the root of the feathers. Frequently the nodules be- 



FiG. 48. A photograph of a section 0/ tubercle from a fozvl, shozving 

 the necrotic center and surrounding zones. Enlarged. 



come confluent. They may or may not involve the subcuta-" 



neous connective tissue. 



The microscopic examination of the tubercles of the liver 

 shows them to consist of a necrotic center surrounded by an 

 irregular zone of epithelioid and giant cells. This is sur- 

 rounded by a band of tissue consisting for the greater part of 

 liver cells more or less disintegrated, free nuclei and a few 

 infiltrated round cells. This zone is circumscribed by a nar- 



