490 DIPHTHERIA IN FOWLS 



irregular and difficult. The mucous membrane of the mouth 

 and phar3'nx is congested and shows numerous dark red eleva- 

 tions covered with fibrinous exudate. The patches on the 

 tongue have increased in size, the}' are gray in color, dried 

 along the edges of the tongue but soft and flattened upon its 

 upper surface. They are covered with membranous deposits. 

 The voice often fails. 



§ 380. Morbid anatomy. The lesions are largely local- 

 ized on the mucosa of the head. With the exception of ema- 



iijif 



(C' 



f 



Fig. 116. A section through a diphtheritic exudate^ late in the course of 

 the disease, from a pigeon's throat. 



ciation, there are no lesions or evidence of organic disea.se. 

 The cause of death and the extreme emaciation are difficult to 

 explain in those cases where the lesions are confined to one 

 eye or to the mucosa of the nares, excepting on the supposi- 

 tion that some poisonous or toxic substance was absorbed 

 from the seat of the disease. In those cases where the lesions 

 are in both eyes, or in the mouth and throat, difficulty in find- 

 ing or swallowing food affords a rational explanation. 



In some cases the exudate is of a croupous character, in 

 others of a diphtheric nature. Three stages or varieties of 

 lesions, which represent the types of this disease as en- 



