  Chas and Sullivan proved the existence of a Batalin-Vilkovisky algebra
structure in the homology of free loop spaces on closed finite dimensional
smooth manifolds using chains and chain homotopies. This algebraic structure
involves an associative product called the loop product, a Lie bracket called
the loop bracket, and a square 0 operator called the BV operator. Cohen and
Jones gave a homotopy theoretic description of the loop product in terms of
spectra. In this paper, we give an explicit homotopy theoretic description of
the loop bracket and, using this description, we give a homological proof of
the BV identity connecting the loop product, the loop bracket, and the BV
operator. The proof is based on an observation that the loop bracket and the BV
derivation are given by the same cycle in the free loop space, except that they
differ by parametrization of loops.
