Yolk Assimilation During the Embryonic Development of the Chick

It has long been established that the chick at hatching time usually has a certain amount of yolk material that has not been assimilated. Since the rate of assimilation of yolk material during embryonic development determines the relatitve amount of unassimilated yolk material at hatching time, it was decided to determine whether chicks from eggs from different hens, or whether chicks from eggs differing in size, or whether male and female chicks vary in respect to the amount of yolk material not assimilated at hatching time. The determination of any differences in respect to any of the cases mentioned might lead to a clearer understanding of some of the fundamental problems involved in the metabolism of the developing embryo, particularly from the standpoint of fat metabolism. The utilization of the fat of the egg by the developing embryo has been investigated and it is apparent that fat is the most . . .