404 Journal of Agricultural Research voi.v.No.g 



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SUMMARY 



The purpose of the present paper is to record the data on the frequency 

 of occurrence of tumors in the domestic fowl which have been collected 

 during eight years' routine autopsy work at the Maine Agricultural 

 Experiment Station. 



The chief points brought out by an analysis of these data are as follows : 

 (i) Of the 880 birds autopsied 79, or 8.96 per cent, had tumors. That 

 is, there were 90 cases of tumors per i ,000 birds. 



(2) There was no significant diflference in frequency of occurrence of 

 tumors between birds which died from natural causes and apparently 

 normal birds which were killed. 



(3) There is a significant positive correlation between age and the 

 occurrence of tumors. Only 7.37 per cent of the birds under 2}^ years had 

 tumors, while neoplasms were present in 19.17 per cent of those that were 

 over that age. 



(4) In birds with tumors which died from natural causes, the tumors 

 were directly or indirectly the probable cause of death in from one-third 

 to one-half the cases. 



(5) There was a decided tendency for the association of hypertrophied 

 (apparently due to cell infiltration) liver, spleen, or kidney with the 

 presence of tumors in other organs. 



(6) Death often resulted from internal hemorrhage from the tumor, 

 the underlying tissue, or the hypertrophied liver or spleen. 



(7) The tumors can be classified into cystic and tissue tumors; 22.78 

 per cent of the tumors were of cystic and 74.68 per cent of solid-tissue 

 structure. There were two cases of tissue tumors to which cysts were 

 attached. 



(8) In the females ^ the organs most frequently affected were the 

 genital organs; 37.76 per cent of all the tumors being in the ovary and 

 18.36 per cent in the oviduct and oviduct ligament. 



(9) In most cases the tumors were confined to one organ. In 15 cases, 

 however, the tumor had evidently undergone metastasis, since tumors of 

 similar nature occurred in from two to four organs. 



' Autopsies were made on too few males to yield reliable data. 



