Nu accroupi dans la baignoire

Nu accroupi dans la baignoire (Crouching Nude in the Bathtub) is one of several works in which Bonnard depicts Marthe fully inside the tub rather than at its edge—the body submerged to varying depths in the intensely blue water that became the most radical chromatic element of the bathroom series. The bathtub as an enclosing form has been interpreted biographically, Marthe's compulsive bathing read as a symptom of the isolation that characterized her later years. Formally, the composition presented Bonnard with the problem of depicting a body both above and below a water surface, a problem he solved through color contrast rather than transparency effects. These works from the late 1930s and 1940s are among his final masterpieces.

The water is rendered in an artificially intense turquoise that reads as a flat color plane rather than a transparent medium, against which the flesh tones of the submerged or partially submerged body glow with unexpected warmth. The tub's white enamel is rendered in a range of off-whites and creams that absorb and reflect the surrounding color. The handling is rich and varied, with some areas built to considerable impasto.