Connection between distribution and fragmentation functions

We show that the quark fragmentation function D(z) and the quark distribution function q(x) are connected in the z → 1 limit by the approximate relation D(z)/z ≃ q(2 - 1/z), where both quantities are in their physical regions. Predictions for proton production in inelastic e⁺e^- annihilation, based on the new relation and standard parametrizations of quark distribution functions, are found to be compatible with the data.