II. Model building: an electrical theory of control of growth and development in animals, prompted by studies of exogenous magnetic field effects (paper I), and evidence of DNA current conduction, in vitro.

A theory of control of cellular proliferation and differentiation in the early development of metazoan systems, postulating a system of electrical controls "parallel" to the processes of molecular biochemistry, is presented. It is argued that the processes of molecular biochemistry alone cannot explain how a developing organism defies a stochastic universe. The demonstration of current flow (charge transfer) along the long axis of DNA through the base-pairs (the "pi-way) in vitro raises the question of whether nature may employ such current flows for biological purposes. Such currents might be too small to be accessible to direct measurement in vivo but conduction has been measured in vitro, and the methods might well be extended to living systems. This has not been done because there is no reasonable model which could stimulate experimentation. We suggest several related, but detachable or independent, models for the biological utility of charge transfer, whose scope admittedly outruns current concepts of thinking about organization, growth, and development in eukaryotic, metazoan systems. The ideas are related to explanations proposed to explain the effects demonstrated on tumors and normal tissues described in Article I (this issue). Microscopic and mesoscopic potential fields and currents are well known at sub-cellular, cellular, and organ systems levels. Not only are such phenomena associated with internal cellular membranes in bioenergetics and information flow, but remarkable long-range fields over tissue interfaces and organs appear to play a role in embryonic development (Nuccitelli, 1992 ). The origin of the fields remains unclear and is the subject of active investigation. We are proposing that similar processes could play a vital role at a "sub-microscopic level," at the level of the chromosomes themselves, and could play a role in organizing and directing fundamental processes of growth and development, in parallel with the more discernible fields and currents described.