My colleagues and I, as well as many other investigators (Pierce 1967; Foulds 1969; Pierce and Wallace 1971; Berenblum 1974; Boutwell 1976; Potter 1978) have performed experiments based on the assumption that those intracellular controls which are involved in the transformation of normal cells into malignant cells are also involved in the generation of diversity among normal cells (Holtzer et al. 1972, 1974, 1975c). In addition, we have assumed that these intracellular controls are the very mechanisms which permit a “cloned” zygote, a “cloned” blastula cell, or a “cloned” limb bud precursor cell in early compartments of their respective lineages to generate diversified progeny (Abbott et al. 1974; Dienstman et al. 1974; Holtzer 1978). In all instances the fundamental question is: How does a single replicating “mother” cell, following a quantal cell cycle, yield daughter(s) with a predictably different, but equally limited, set of metabolic options? A replicating blastula cell, a replicating erythrogenic hematocytoblast or Friend erythroleukemic cell (Holtzer et al. 1972, 1975c; Lajtha and Schofield 1974; Weintraub 1975; Holtzer 1978), a replicating presumptive chondroblast (Holtzer 1978), or a replicating presumptive myoblast (Holtzer et al. 1975c; Holtzer 1978) has no option following a quantal cell cycle, but to yield specifically different kinds of gastrula cells, erythroblasts, chondroblasts, and myoblasts, respectively. Presumably, daughter cells, as a consequence of a quantal cell cycle, acquire the capacity to transcribe regions of the genome that could not be transcribed in their mother2. It is equally likely that the daughter cells lose the capacity to transcribe regions that were uniquely transcribed in their mother cells. Similarly, embryonal carcinoma cells (Martin 1975), chondrosarcoma cells, hepatoma cells, or lymphoma cells have each inherited a different set of metabolic options which (1) not only distinguish these different types of neoplastic cells one from the other, but (2) distinguish them from their normal mother cells.