A number of reports suggest a close relationship between the development of ribulose-1,5-diphosphate (RuDP) carboxylase and chlorophyll in higher plants, algae and photosynthetic bacteria. Fuller and Gibbs (2) have shown that RuDP carboxylase activity is low in albino barley mutants compared with the levels in green barley. Streptomycinbleached Euglena contains a lower amount of RuDP carboxylase activity than light grown Euglena. The synthesis of RtuDP carboxylase and bacteriochlorophyll occur at the same rate in Rhodopseudomonas spheroides (6).. Smillie (7) has shown the increase in the photosynthetic rate in greening leaves parallels the development of RuDP carboxylase and photosynthetic pyridine nucleotide reductase. Huffaker et al. (4) have also shown a high degree of correlation in the rate of synthesis of RuDP carboxylase and chlorophyll in greening leaves. In this communication we show that the level of RuDP carboxylase in growing virescent cotton leaves is normal or higher than the level in control green leaves. The virescent leaves show a pronounced lag in chlorophyll development. There is no significant correlation between the rate of synthesis of RuDP carboxylase and chlorophyll in mutant leaves. Vires,ent i(5) and normal green cotton plants (Gossypium hirsutum L.) were grown in the field. Plants which had developed about 11 nodes were used for experiments. Leaves from the same node from several plants were collected. The leaves were rinsed with distilled H20 and blotted. The main veins were removed and a portion of the leaves were used for chlorophyll analysis by the method previously described (1). The remainder of the leaves were ground in a chilled mortar in 0.1 M tris buffer pH 7.5 containing 1 mM GSH and sand. The brei was squeezed through 2 layers of cheesecloth and centrifufged 20 min at 27,000g in a refrigerated centrifuge. The supernatant fraction was removed and centrifuged in a 50 rotor at 50,000 rpm for 60
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