Formation of chlorophyllide a by the extraction of chlorophyll with pure or 80% buffered acetone. Frozen leaves were immersed in pure acetone or 80% acetone containing 20% (v/v) Tris–HCl, pH 8 and then incubated in these solvents for 12 h at 4°C in the dark. Pigments were subsequently extracted by grinding with stainless steel beads as described in the Methods section. A. Levels of chlorophyll a and chlorophyllide a per gram fresh weight of leaves. B. Chlorophyllide a levels in sample extracts expressed as the ratio of cholorophyllide a to the sum of chlorophyll a and chlorophyllide a. Chl a, chlorophyll a. Chlide a, chlorophyllide a. Error bars indicate standard deviations. Sample size, n = 3.