8 MASS. EXPERIMENT STATION BULLETIN 370 



son and others 163), lymphomatosis (Johnson 107), Mareksche Gefliigellahmung, 

 neuromyelitis, paralysis, and neurolymphomatosis gallinarum (Pappenheimer 

 et al. 160). 



The essential features of the pathological anatomy of this disease have been 

 well described by numerous workers (Kaupp 119, Pappenheimer, Dunn, and 

 Cone 160 and 161, Patterson, Wilcke, Murray, and Henderson 163, Warrack and 

 Bailing 214) and will be considered only briefly. The symptoms consist of an 

 asymmetrical, partial, and progressive paralysis of the legs or wings and less 

 often of the neck muscles. There are occasional cases in which a gray discolora- 

 tion of the iris may be noted. The duration of the disease is variable and some 

 individuals may recover although death is the usual result. The principal path- 

 ological changes are to be found in the dorsal root ganglia of the spinal segments 

 and the peripheral nerves. These changes are an infiltration of polyblasts (lym- 

 phocytes, histiocytes, and plasma cells) in the nerve trunk with myelin degenera- 

 tion and increase of the Schwann sheath cells. Sometimes the infiltrating cells 

 assume an almost neoplastic aspect and undergo marked proliferation. Perivas- 

 cular accumulations of mononuclear cells may occur in the central nervous system. 

 The changes in the eye associated with the disease consist of an iridio-cyclitis 

 in which polyblasts are the infiltrating cells (Jaensch and Lerche 96). Visceral 

 lymphocytomas, usually of the ovary, are found in a variable percentage of 

 the cases. No marked alterations of the peripheral blood are associated with the 

 disease (Johnson and Conner 111, Jungherr 113, Beach and Twisselmann 10). 



Potel (165 a) studied 32 hens affected with fowl paralysis, 11 of which had 

 neoplastic-like lesions in the visceral organs. He came to the conclusion that the 

 disease was neoplastic rather than inflammatory in character and that fowl 

 paralysis and fowl leukosis were but different manifestations resulting from the 

 action of a common causative agent. Fritzsche (68 a) states that this conception 

 of Potel's is untenable even on the basis of a study of the pathological cells alone 

 without considering the epizoology and results of experimental transmission. 

 The latter two factors cause the distinction between the two diseases to be still 

 more evident. 



Both successful and unsuccessful attempts at experimental transmission of 

 fowl paralysis have been reported. Some investigators believe that fowl paralysis, 

 lymphocytoma, and transmissible fowl leukosis are caused by a single disease- 

 producing agent. Others have come to the conclusion that one agent may cause 

 fowl paralysis and lymphocytoma. These relationships have been mentioned in 

 the section dealing with lymphocytoma. The investigators who have reported 

 the successful transmission of fowl paralysis by means of experimental inoculation 

 are Pappenheimer, Dunn, and Cone (160), Pappenheimer, Dunn, and Seidlin 

 (162), Patterson, Wilcke, Murray, and Henderson (163), Seagar (179), Jungherr 

 (115), Johnson (108), Lerche and Fritzsche (128), Furth (79, 80). Other early 

 contributions dealing with the role of parasites in the etiology of fowl paralysis 

 have been reviewed by Biely and Palmer (14). Unsuccessful attempts at ex- 

 perimental transmission of the disease were reported by Kaupp (119), Doyle (30), 

 Jungherr (113), Dalling and Warrack (28), Barber (4), Beach (9), and Olson 

 (156). Some investigators have advanced the idea that the disease may be 

 transferred from the parent to the offspring. Gibbs (88) described what he 

 considered to be the pathological type cell in the semen of male chickens and 

 suggested that these cells might infect the eggs fertilized with such semen. He 

 also described the pathological type cell in the follicular fluid of the ovules. 

 While this is an entertaining conception, there are almost insurmountable difficul- 

 ties attendant upon the identification of a cell which may be said to be specific for 



