2 Mn tm Be ae A ERIERSTRIE DIFFERENTIATION OF GASTRULAS AND FEATHER GERMS1005 (yo : ) Fig. 6 —Seven-day-old chick embryo skin cultivated for 5 days. (0) Irradiated with 1000 R (no feather germs), (a) Control. Fig. 7—Results of the reassociation of normal dermis and normal epidermis. Magnification, 240%, Cc a neAr en oe ae