SummaryThe problem of fruit size in the Australian apple variety Granny Smith was examined in relation to mean cell size and mean cell number. Cell size gradients in the fruit and changes in cell shape and packing during development were noted.Observations of workers on other varieties that cell division ceased within four weeks of pollination were confirmed. Variation in size of fruits at maturity was shown to be due mostly to variation in cell number and only to a small extent to mean cell size. Cell enlargement was shown to continue throughout the life of the fruits on the tree.

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Morphological, anatomical, submicroscopical, and physiological changes in whole seeds and embryos of Pisum sativum L. cv. Victory Freezer were followed during 54 days of development of the seed. Four developmental phases-cell formation, cell expansion, synthesis of storage reserves, and maturation and dormancy-were recognized in the development of the embryo. Each phase was characterized by a distinctive physiology and a distinctive subcellular organization of the parenchyma cells. The subcellular organization associated with carbohydrate, protein, and fat metabolism and the significance of membranes in cell organization is described.

Superficial scald in Gl'Rlllly Smith apples has been examined by electron microscopy, and a detailed picture of the changes in cell structure as macroscopic scald symptoms develop has been obtained.

Stages in the development of the outer layer of the vitelline membrane of a hen's egg have been observed in an egg found in the infundibulum of a sacrificed White Leghorn hen. Tissue from the infundibulum and the underlying egg yolk material was taken at increasing distances from the upper end of the egg and the relationship between the secretory cells of the infundibulum and the vitelline mem-brane observed. The structure of the vitelline membrane in ova just liberated from the ovary and not yet in the oviduct and that of the vitelline membrane in new-laid eggs from other White Leghorn hens were observed for comparison.