Abstract There is abundant evidence that egg production in the domestic fowl is a character that is amenable to selection, especially if the progeny test is applied. The work of Pearl and Dryden, especially, substantiates this statement. I have shown further that it is a character complex, and that certain of the elements of this complex are readily recognized. Viewed from the selection standpoint, it is evident that egg production is an example of a primary character, viz., ability to produce eggs, their number and distribution being determined by several modifying factors of genetic origin. Having reached the conclusion that egg production is a character complex, the next step, obviously is to establish the genetic character of each element of the complex, and to work out the mode of inheritance of each element. This has been attempted, but the results are limited largely to families characterized by certain elements of the …