Fig. 5. Mitotic figures isolated from fertilized sea urchin eggs (Mazia and Dan, 1952; 

 Mazia, 1956). Upper photograph: most figures are in metaphase or anaphase. Lower 

 photograph: high-power view of isolated mitotic apparatus at anaphase. 



Fig. 6. Electron micrograph of isolated nucleolus from isolated nuclei of pea embrj^o 

 (Johnston e.t ah, unpublished). 



