SYMPTOMS 541 



be the exciting cause. The disease is readily transmitted by 

 inoculation. Ward has produced it by simply pricking the 

 tumor with a syringe needle and then puncturing the skin on 

 the head of a healthy chicken Marx and Stickler ground up 

 the tumors or nodules in normal salt solution and passed this 

 through a Berkefeld cylinder. The filtrate rubbed on the 

 scarified combs of healthy chickens produced the disease. The 

 virus did not pass through the porcelain filters. 



§ 430. Symptoms. The disease first manifests itself by 

 a catarrh of the mucosa of the head. In the further course 

 of the disease wart-like proliferations appear on the mucosa 

 and extend to the skin. The epitheliomata are usually at 

 first gray and glistening but later they are covered with a scab. 

 The nodules may become so numerous, or if single so large, 

 that the eyes are closed, in which case the fowls being unable 

 to see may die from starvation. The growths may also inter- 

 fere with the use of the beak. The lesions are usually local 

 on the unfeathered part of the head. They are said at times 

 to extend to the feather covered skin. The affected fowls are 

 used for food unless there are objectionable secondary changes 

 resulting from lack of ability to eat. Recover}- often takes 

 place in from three to four weeks. 



§ 431. Morbid anatomy. The nodules consist of epi- 

 thelial cells. There is a cell infiltration of the skin and sub- 

 cutaneous tissue. The epithelial cells are much larger than 

 normal; they may be in scales or in more dense masses. Later 

 in the course of the disease the nodules may drop off as scales. 



RKFERENCES. 



1. Boi.T^iNGER. Ueber Epithelioma contagiosa beim Haushuhn 

 nnd die sogeiianiiten Pocken des Gefliigels. Archiv. fi'ir. Path. Anal., 

 Bd. LVIII (1873), S. 349. 



2. Heusinger. J^echerc/ies de Path. Coinf)., Vol. i, (1847), 

 p. 649. 



3. Salmon. Diseases of Poultry . 



4. Sedgwick. Chickens and their diseases in Hawaii. Jliillclin 

 No. /, Haivaii Agric. Exp I. Station, 1901. 



