An example.- The extension of branches of solutions for nonlinear equations in Banach spaces.- Development of branches of solutions for nonlinear equations near an exceptional point. Bifurcation theory.- Solution of the bifurcation equation in the case n=1; bifurcation at the origin.- The eigenvalue problem; hammerstein operators; sublinear and superlinear operators; oscillation kernels.- On the extension of branches of eigenfunctions; conditions preventing secondary bifurcation of branches.- Extension of branches of eigenfunctions of Hammerstein operators.- The example of section 1, reconsidered.- A two-point boundary value problem.- Summary; collection of hypotheses; unsettled questions.