K. Rith

Experimental results obtained at the CERN Super Proton Synchrotron on the structure-function ratio ${\mathit{F}}_{2}^{\mathit{n}}$/${\mathit{F}}_{2}^{\mathit{p}}$ in the kinematic range 0.004x0.8 and 0.4${\mathit{Q}}^{2}$190 ${\mathrm{GeV}}^{2}$, together with the structure function ${\mathit{F}}_{2}^{\mathit{d}}$ determined from a fit to published data, are used to derive the difference ${\mathit{F}}_{2}^{\mathit{p}}$(x)-${\mathit{F}}_{2}^{\mathit{n}}$(x). The value of the Gottfried sum F(${\mathit{F}}_{2}^{\mathit{p}}$-${\mathit{F}}_{2}^{\mathit{n}}$)dx/x=0.240\ifmmode\pm\else\textpm\fi{}0.016 is below the quark-parton-model expectation of 1/3.