Like isolated chloroplasts, the volume of chloroplasts in living cells of Nitella flexilis decreases reversibly with illumination. This process was recorded by flashlight photography in the same cell and with the same chloroplast. These changes of volume are anisotropic and are caused by a decrease of the chloroplast thickness. The degree of shrinkage depends upon the age of the cells. A dependence of the light intensity was demonstrated. The correlation between fine structure of Nitella

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... lasts and of swelling and shrinkage phenomenon is discussed.