NEUROLYMPHOMATOSIS IN CHICKENS 7 



were not fine enough to detect them. It was ph\sicall\- impossible to examine 

 all of the birds histologically. Table 1 shows the results of the necropsies of 304 

 birds from seven different flocks and the tabulation of the names of the nerves 

 affected with neuroKiniihomas. 



Table 1. Location of Neukolymphomas 



Flocks 



Nerve 



Sciatic 41 69 31 8 I,'', 20 13 



Vagus 39 35 30 6 14 27 12 



Brachial 29 28 12 3 20 19 5 



Celiac 12 3 9 4 7 15 10 



Optic 6 



Mesenteric 5 



Crural 1 



Peroneal 3 



Costal 



Cer\'ical 



Plantar 1 



Laryngeal 2 



Meningeal 1 



Cocc\geal 



Number of Birds 91 92 32 10 25 30 24 



This table shows that the sciatic, \"agus, brachial, celiac, and optic ner\"es 

 were most commonly affected. A comparison of Flock A with Flock F shows 

 some important differences. In Flock A the sciatic nerves were most commonly 

 involved, while in Flock F the involvements occurred largeh" in the vagus and 

 brachial ner\es. This may indicate flock specificitx', but it cannot be definiteh* 

 proved for all of these flocks represent different blood lines and the distribution 

 of the neurolymphomas are rather uniform, except in Flock F referred to above, 

 and Flock G, in which the optic nerve was frequently' involved. 



It was noticed that birds received from flocks on the range often impro\ed 

 after being isolated in individual cages. Histological and hematological examina- 

 tions of the tissues and blood indicated that these birds were holding their own, 

 temporaril}- at least. The pathological cell involved in neurolymphomatosis 

 was not found in the blood and tissues outside of active lesions, which indicates 

 that there was some antagonism to the disease. There was no laboratory evidence 

 to indicate that this antagonism was due to immunity. The disease tends to 

 lessen in severit}' after existing in a flock for two or three years, which demonstrates 

 clinically that either some degree of immunity is developed or the susceptible 

 birds die, leaving the more resistant to reproduce future generations. Three 

 birds, apparently showing acti\"e symptoms of paraKsis, recoxered and at nec- 

 ropsx' no lesions of disease were found. 



