The parent cubic phases of alloys which undergo martensitic transformations exhibit various pretransformational effects including the development of fine-scale periodic strain modulations. This diffuse microstructure, revealed by electron microscopy and diffraction, is identified as a dense array of incommensurate shear strains of {110} <[MATH]> type. This behavior, which results in an incipient loss of cubic symmetry, appears to be related to the concurrent parent lattice softening (i.e. the decrease of C' with decreasing temperature approaching Ms) that is observed in most of the same alloys