256 



VETERINARY rATUOLOGY. 



to the solar heat ravs or thernio-cautery. Necrosis induced by 

 freezing is very common in calves, pigs, and chickens, in the 

 tenijK-rate and frigid zones. 



Chemic necrosis is represented by the extensive destruction 

 of the buccal, oesophageal, gastric, and intestinal tissues induced 

 by the ingestion of lye. Corrosive suldimate and arsenious tri- 

 nxide destrov the mucous membrane and frequently the deeper 

 tissues of the alimentary tract in animals poisoned with these 

 agents. 



Location. — Xccrnsis may be surface or subsurface. Surface 



Fig-. 134. — l]rjj<»t roihoninjJT in tattle. Photograph by Dr. W. T. Sponccr. 

 l-^louShin.!j aljovu the Icit. :;. Sloughing ot the LTids of thr talis 



necrosis may be nf the skin, mucous or serous membranes. Sub- 

 surface necrosis may be of any tissue, muscle, bone, glandular, 

 etc. 



Xatiirc or condition of the necrotic tissue. 



1. Coagulation necrosis. — This type of necrosis is character- 

 ized by the coagulation of the necmtic tissue. It is the result of 

 the presence of sume enzym that ])r()duces the formation of fibrin 

 or some allied substance. Coagulation necrosis is evident in the 

 coagulation of blood and inflammatory exudate,?. The exudate 

 in fibrinous inflammation (croupous and diphtheritic) usuallv 

 becomes firmly coagulated. On the other hand, coagulation is 

 rarely obser\-ed in collections of lym])h, as in ascites, etc. The 

 necrotic tissue in anemic infarcts, especially in the kidney, is 

 sometimes coagulated. 



2. Colliquation necrosis. — The condition resulting from solu- 



