Gravity's Rainbow

by Thomas Pynchon

What are we to make of Gavin Trefoil, for whose gift there’s not even a name yet? (Rollo Groast wants to call it autochromatism.) Gavin, the youngest here, only 17, can somehow metabolize at will one of his amino acids, tyrosine. This will produce melanin, which is the brown-black pigment responsible for human skin color. Gavin can also inhibit this metabolizing by—it appears—varying the level of his blood phenylalanine. So he can change his color from most ghastly albino up through a smooth spectrum to very deep, purplish, black. If he concentrates he can keep this up, at any level, for weeks. Usually he is distracted, or forgets, and gradually drifts back to his rest state, a pale freckled redhead’s complexion. But you can imagine how useful he was to Gerhardt von Göll during the shooting of the Schwarzkommando footage: he helped save literally hours of make-up and lighting work, acting as a variable reflector. The best theory of how is Rollo’s, but it’s hopelessly vague—we do know that the dermal cells which produce melanin—the melanocytes—were once, in each of us, at an early stage of embryonic growth, part of the central nervous system. But as the embryo grows, as tissue goes on differentiating, some of these nerve cells move away from what will be the CNS, and migrate out to the skin, to become melanocytes. They keep their original tree-branch shapes, the axon and dendrites of the typical nerve cell.