The fine structure of isolated Acetabularia nuclei

Summary Acetabularia nuclei were isolated in solutions of sucrose and fixed, dehydrated and embedded for electron microscopy using a number of techniques. The dimensions of the nucleic changed during all the procedures used, but the addition of calcium to the fixative prevented swelling. The structure observed in isolated nuclei was in good agreement with that seen in nuclei in intact cells and amputated rhizoids. A layer of cytoplasm about 0.1 thick was found on the outside of even the cleanest nuclei — this layer probably gives the nucleus protection when it is isolated.