Lymphomatosis in Chickens as Influenced by Diallel Crossing

CONSIDERABLE experimental evidence contributed by numerous investigators warrants the assumption that certain strains, lines, or families of chickens live longer than others and that viability is influenced by parental selection and hence lends itself to genetic interpretation. Unfortunately chickens in general are beset by many diseases, parasites, and physiological disturbances which shorten their life span. It becomes exceedingly difficult in a genetic study which has, as its objective, selection for resistance or for susceptibility to a specific disease, to be sure that death was influenced only by the disease under consideration. Those studies which have been conducted on general viability of groups of chickens list numerous reasons for death. Indeed, studies which involve selection for a particular disease are influenced considerably by losses from other causes. Hutt et al. (1941) show in their studies on resistance to neoplasms that deaths from other causes exceeded those from the neoplasms. Waters (1945a) . . .