Plant protoplasm in buds and leaves is an hydrosol that probably behaves like oil-in-water emulsions in freezing. Hence, information about freezing phenomena in emulsions is physiologically significant as related to freezing phenomena and winter hardiness in plants. Microscopic freezing phenomena in cresoap emulsions of oils were: (a) Needles and lamellae of ice invaded fields of oil globules, arranged them in rows, and caused many of them to coalesce. Compound ice crystals enlarged until adjacent ones were separated only by narrow spaces, (b) Above these spaces, other layers of ice enclosed irregular masses of oils, gas, and aqueous solutions in irregular channels. Part of the oil globules were re-dispersed when emulsions melted. As emulsions froze in test tubes, clear ice formed near the glass, concentrating the emulsions in the centers. Then masses of pure ice formed in the emulsions enclosing oils, emulsifiers, and gas in their interstices. The freezing columns changed from milky to non-milky appearance, expanded, and formed horizontal milky cracks. As thermal motions of molecules decrease below 0[degree] C, the attractive forces causing crystallization increase until they exclude impurities and aggregate the hydrogen and oxygen of water into crystals of pure ice. This explains why the dissolved oxygen, nitrogen, cresols, and soaps were excluded from crystallizing water: they were concentrated and enclosed between the ice crystals. Freezing injury to plant cells is reduced by substances that retard the release of water for crystal formation, and by substances that facilitate re-emulsification.