The most formally resolved of the small-scale abstract watercolors — a work of such compositional clarity and chromatic confidence that it could stand beside any mid-century American abstract work without apology. The composition is organized around a single large closed curve — a fat blue arc that sweeps from upper left through the upper right and back down to lower center, enclosing most of the picture field like a cell membrane or the outline of an egg.
Within this enclosure, a secondary world operates: a large purple teardrop form at center-left, its interior containing a smaller red shape that suggests a nucleus or seed; to the right, a green rectangular field with simple marks — two vertical lines and a small square — that read almost as notation or architectural plan; scattered small elements throughout — yellow dots, a small red diamond, tiny marks in teal and coral.
Outside the enclosure, at upper left, a green sphere with two red slashes — emphatic and independent, its own complete statement. The relationship between the sphere outside and the world inside the blue curve is the painting's central tension: what is in and what is out, what is contained and what is free.
The blue arc itself is extraordinary — thick, textured with the granular quality of cobalt blue in watercolor, its edge slightly irregular in a way that communicates both intention and the natural behavior of the medium. This is a stroke made with confidence and allowed to be what it is.
The suggested title names the biological reading that the composition invites most strongly: a cell, with its membrane and nucleus, seen with the kind of attention that Sidney brought to everything — curious, precise, transformed by his imagination into something that is at once observed and invented.