Hello Jim, yes, they are adjacent; the walls of each grain forms an elision with its neighbors . . . and the ongoing elision of shared walls is the background (bubble bath simile later in that paragraph).

TMI for here but, the space-time properties of each grain are without measured value. That is, they are abstract, and they form a non-spacial, non-temporal perimeter wall, or border which tells the grain, among other things, to “end here.” The actual volume of the grain is its one measured, or “discrete” property. For the sake of clarity, the diagrammatic drawings show discretely voluminous grains set within a dimensioned realm of abstraction but, of course, true abstraction (in this case, the laws and unmeasured properties of space-time) has no spacial dimension.

Thanks for your response, and for your consideration of the idea!