  Let X be a complex submanifold of projective space. Schnell showed that the
middle-dimensional primitive cohomology of X is generated by tube classes,
which arise from the monodromy of the vanishing homology on hyperplane
sections. Clemens asks if the theorem is still true when we restrict the
generating set to the tube classes over the class of a single vanishing sphere
of nodal degeneration. We prove this is true for hypersurfaces in CP^4. The
proof is based on the degeneration of a hypersurface to the union of
hypersurfaces of lower degrees.
