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.