Integrated intensities of the 2_1,2–1_1,1 (E₂) transition of methanol (red contour) and 3_2,2–3_1,3 transition of cyclopropenylidene (black contour) are plotted on the H₂ column density map derived from far-infrared images observed by Herschel (Pilbratt et al. 2010). The contour levels are 10σ, 15σ, and 20σ CH₃OH (2 × 10^-1, 3 × 10^-1 and 4 × 10^-1 K km s^-1, respectively) and 5σ, 10σ, and 15σc-C₃H₂ (4.8 × 10^-2, 7.2 × 10^-2 and 9.6 × 10^-2 K km s^-1, respectively). The white box defines the area that was mapped with the 30 m telescope. The white cross marks the position of the 1.2 mm dust emission peak from Ward-Thompson et al. (1999). The beams of SPIRE and of the 30 m telescope are shown as a white and blue circle, respectively. The dotted line represents the positions where the column densities plotted in Fig. 3 have been extracted. Methanol and cyclopropenylidene clearly trace different regions in L1544, and show a chemical differentiation within the prestellar core.