Embryonic development can be observed in more than 50% of the unfertilized eggs after 10 days of incubation. The eggs are obtained from a strain of turkeys selected for a high incidence of parthenogenesis by Dr. M.W. Olsen at Beltsville, Maryland. A small proportion of the eggs contained embryos which, although retarded, appeared normal. However, a large proportion of the eggs contained masses of membranes. Examination of the eggs after 1 to 4 days of incubation showed a few embryos with a definitive primitive streak. However, most of the embryos were without a definitive primitive streak, although a slipper-shaped area pellucida was present. Periodic examination of embryos without a primitive streak reveal that they continue to develop into membrane-type embryos. We propose to determine the developmental potential of these membrane-type embryos by grafting pieces of area pellucida on to the chorioallantoic membrane of a 10-day chick embryo. We will also attempt to induce differentiation or organization in these membrane-type embryos by grafting Hensen's node from a normal chick embryo onto the anterior portion of the area pellucida of parthenogenetically developing turkey embryos which do not have a primitive streak.