A native Malaysian girl tree tapper at work, on February 3, 1943. Considerable skill is required for the tapping of a rubber tree, as the latex lodges against thin layers of cells that separate bark from wood. As these cells always run in a downward direction, from right to left, the cut usually is at a 30 degree angle in the opposite direction, from left to right, if too deep the bark will not reproduce; if not deep enough the yield is diminished.