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Imagine reaching through a sausage skin from one end, grabbing the other end and pulling it back towards you, then joining the two ends together. You've made a torus. Now fill the space enclosed between the two layers with protoplasm, and suppose the skin of the torus to be cell membrane. You've made a cell with unusual properties that Pivar refers to as "germ plasm".
For this cell to become mobile, imagine the skin on the inside crawling or being pulled towards one end. The torus as a whole will move, like a tank, as it extends its skin at one end and pulls it up inside at the other. This would allow it to migrate within a cluster of such cells.
If cuts across the torus are self-healing it will duplicate itself. If it could continuously grow itself then by repeated budding it could duplicate itself endlessly to form masses of similar cells or columns of them to form segments.
Form could be generated in the developing embryo by what happens to the inner surface of the torus as it is compressed to fit within the outer surface. As that inner surface is squeezed it could be compressed into three, four or five evenly-spaced "spokes," with or without bulbs at the ends that become new tissues. This is how an everted blastula could generate a complex cross section that through further differentiation and growth could become organs, bones and muscle blocks. Now imagine a torus sending out an extension. This extension could now take on similar forms to become antennae or limbs. Finally, such tori can be imagined splitting across into circular disks and along their sides to form flat sheets.
Summary: this urform is how specifications for the basic forms of a living creative could be passed on from egg to egg and from one cell to each of many cells, and what could generate form in early development in the embryo. That much I got from a first reading of Stuart Pivar's The Urform Theory: Evolution Without Darwin. And it's a lot. I found the idea plausible and persuasive. This could account for the generation and replication of characteristic cell, tube, segment and sheet elements of living tissues.
Having a generator of 3D form elements that could be programmed through a sequence of instructions would nicely narrow our prescription for a complete mechanism for development and evolution. A generator of form such as this urform surely must synch with some higher-order system that directs its growth and development. Mating among birds of paradise combines form with characteristic movements and colors and sounds, so the control of form is not separate from control of other aspects of performance. And in the embryo form and time are intricately connected.
What must that system consist of? Something like video editing software, with multiple control tracks arranged parallel over time. There would be channels for form that manage the growth and development of urform elements, channels calling on protein production, other channels of switches for turning sub-channels on and off, and so on. For me, having something like the urform provide a three-dimensional form-generation capability helps by reducing form to merely one of many quite similar linear time-linked control capabilities. This nicely ties in with recent research on the role of the genome in the direction of life processes, as reported in James Shapiro's "Evolution: View from the 21st Century."
If we imagine life to be controlled from such a multitrack dashboard, the same in essence for all life but differing from species to species in the programming of the tracks, then we can refer all living processes to it, including development, homeostasis, repair, and evolution. Such a dashboard has been implied in books such as Shapiro's. We may even see evolution in terms of the organization and increase in number of these tracks over time. We could reinterpret Lamarckism's two mechanisms thus: use and disuse result in shifting settings along the tracks, major creative leaps involve the additions of new tracks
This could give us an improved context in which to consider mechanisms of evolution. For example, one might ask, could such a dashboard evolve through selection of point mutations of genes? Change of settings in a channel, perhaps yes. The addition of new channels, perhaps not. And, how is the time dimension maintained constant across all the tracks? Can that be specified by the genome, or is it a property of protoplasm?
Pivar's promotion of the urform concept encourages major rethinking about living processes.