  Motivated by recent discovery of colossal magnetoresistance in
La$_(1-x)$Ca$x$MnO$_3$ and other manganites, we have studied the double
exchange model. We argue that the forced alignment of conduction-electron spin
with the core spins that causes ferromagnetism also projects out a large part
of the Hilbert space needed for coherent propagation of electrons carrying spin
and charge. As a result, the electron becomes a composite object and its
Green's function exhibits a two-fluid character: a coherent Fermi-liquid
component associated with the ferromagnetically ordered core spins, and a
non-Fermi liquid component associated with the disordered spins. With
increasing temperature, there is continuous transfer of spectral weight from
the Fermi liquid to the non-Fermi liquid component, until the former disappears
above $T_c$. In an applied field spectral weight is transferred from the
non-Fermi liquid to the component. Implications for the manganites are
discussed.
