Modified Method of Carbon Marking

Abstract

IN the field of experimental embryology, carbon marking has been widely used for tracing the movements of cells¹. By this method blood carbon particles adhering to the end of a needle are deposited among the cells the migrations of which are to be studied. When experiments are carried out in ovo, the needle, before it reaches the embryo, must first pass through the overlying layer of saline, albumen, etc., and the surface-tension effects here, as the needle reaches the surface of this fluid, cause the removal of all the particles not adherent to its very tip. To minimize this effect, it is essential that the needle be held perpendicular, and that a quick stabbing movement be used.