Excrement is big this September -- Andres Serrano’s luscious photographs of feces can be seen at Yvon Lambert Gallery on West 21st Street, and a group show called "Shit" is the first exhibition at Feature’s new space on the Bowery. And the artist Sue Williams, now showing at David Zwirner Gallery, has long been involved with poo, as well as blood, semen and vomit. Bodily fluids and solids of all sorts (and the actions involved in producing them) were among her main subjects when she first gained notoriety for her scathing representations of sexual warfare in the early 1990s. She subsequently transformed her gritty depictions of angry encounters into airy abstractions that resemble finicky late works by Willem de Kooning. Allusions to bodies remain, but her colors glow with painstaking finesse.