An electron microscopic analysis of replication intermediates in chromosomal DNA from several systems has been made. In all of them, besides entirely double stranded molecules, only molecules with clustered small “eyes” and partially or entirely single stranded molecules were observed. Early cleavage embryos of D.melanogasteralone showed the presence also of molecules with long replication “eyes”. These patterns strongly support a unifying interpretation we recently proposed for chromosomal DNA replication in eukaryotes.