The ultrastructure of the plastids from the genetically caused but maternally transmitted mutant iojap of maize was studied at four stages of development. The plastids of green and potentially green tissue were normal at all stages studied. The plastids of the white tissue were aberrant at all stages studied and lacked the normal grana‐fretwork system as well as a normal prolamellar body. DNA‐like fibrils were present in aberrant plastids, but ribosomes were absent. This indicates that chloroplast ribosomes are important in chloroplast membrane formation. Aberrant plastids fail to develop normally and are not a degeneration of normal plastids. Aberrant and normal plastids occur in single cells in green tissue, but only aberrant plastids have been found in white tissue.

Chloroplast stroma crystals similar to those reported by PERNER (1962, 1963) but different from those described by other workers were demonstrat ed in Vicia faba chloroplasts. They were absent in chloroplasts isolated in no sucrose, 0.3 M sucrose or in situ material either fixed in the absence of sucrose of fixed in the presence of 0.3 M sucrose. They were present in chloroplasts isolated in 0.5 M sucrose and in situ chloroplasts fixed in the presence of 0.7 M sucrose.

Protein bodies induced in tomato leaf cells by wounding were shown to contain proteinase Inhibitor I by using ferritin-labelled antibodies, fluorescein-labelled antibodies, and cytochrome C-labelled antibody fragments. Both pre-embedding and postembedding techniques were used. Nonspecific binding was least when p-formaldehyde was used as the initial fixative followed by treatment with cytochrome c-labelled antibody fragments.

Electron microscopy of leaves of tomato has shown that tissue containing chymotrypsin inhibitor I protein has protein in the cell vacuoles. The vacuolar protein was found either as many small bodies or as few large bodies. The data indicate that the vacuole is a temporary storage site for protein which may play an important role in growth and development of the plant. This strongly suggests that the plant-cell vacuole is something more than a site for terminal deposition of waste products. The system offers an unusual opportunity to study the biochemistry and ultrastructure of synthesis, vacuolar deposition, and recall of a well-characterized plant protein.

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