II. REPLICATION OF DNA IN CHROMOSOMES 



105 



Fig. 11. Helical structures revealed by the electron microscope in interphase 

 nuclei of Amoeba proteus. These helices appear to be attached along an axis 

 which is assumed to represent a portion of a chromosome after replication according 

 to the hypothesis in the text. (Photograph from Pappas and Brandt, 1960.) 



