Large sublimed leaflets of titanium trichloride have been observed over a wide range of magnification both by optical and electron microscopy under conditions such that ethylene polymerization was slow enough so that its progress could be observed in detail. After treatment with triethylaluminum, a network of cracks develops on which polymer grows upon introducing ethylene. Polymer also appears on steps, crushed areas, and cleaved edges but not on as-grown edges. The polymer appearing on lateral surfaces was nodular in character while that growing on basal surfaces was fibrous. The physical properties of these two forms may be different, and methods for favoring one or the other are suggested.