Ernest Bloch, Quintet for Piano and Strings, Mvt. I, Agitato, mm. 1-3
Bloch does not employ a full set of quarter-tone accidentals; the small slashes to the left of the notehead indicate that a pitch should be raised by one quarter tone. In general, when composers use ancillary signs (like these slashes) to adjust pitch, they are using quarter tones as auxilliary microtones to embellish an otherwise conventionally-tuned texture.