Abstract A variety of substances may be introduced into the egg by immersing 2-4 cm. of the pointed end into prepared solutions (Seltzer, 1956). We have inhibited or eliminated the development of the bursa of Fabricius by dipping the egg into varying concentrations of testosterone propionate (Glick, 1964). We have attempted to determine the amount of testosterone propionate (TP) that enters the egg by a bioassay procedure (Wilson and Glick, 1966) or by measuring theμl. of solution removed per egg (Sato and Glick, 1964). In 3 of 5 bioassays 54 μg. of TP was found in the albumin 20 minutes after dipping the egg in 640 mg. TP per 100 ml. ethyl alcohol (EA). The values in the two remaining bioassays exceeded 100 μg. TP yielding a mean for the 5 experiments of 81 μg. Measuring the volume of Ea removed per egg suggested that between 74 and 111 μg of.…