In part I of the work J. Appl. Phys. 3547, 1964, a mechanism for the deformation of crystalline polyolefin polymers was proposed. In this paper, the implications of the deformation theory are examined in more detail, and the theory is modified to more exactly account for observations. More critical studies are reported using uniaxially crystallized samples. The variation of properties in a series of ethylene-propylene copolymers is studied and explained in terms of the proposed mechanisms.