Loop structures in Taylor towers

We study spaces of natural transformations between homogeneous functors in Goodwillie's calculus of homotopy functors and in Weiss's orthogonal calculus. We give a description of such spaces of natural transformations in terms of the homotopy fixed point construction. Our main application uses this description in combination with the Segal Conjecture to obtain a delooping theorem for connecting maps in the Goodwillie tower of the identity and in the Weiss tower of BU (V). The interest in such deloopings stems from conjectures made by the first and the third author [ 4] that these towers provide a source of contracting homotopies for certain projective chain complexes of spectra.