  The configurations taken by polymers embedded in out-of-equilibrium baths may
have broad effects in a variety of biological systems. As such, they have
attracted considerable interest, particularly in simulation studies. Here we
analyze the distribution of configurations taken by a passive flexible chain in
a bath of hard, self-propelled, vibrated disks and systematically compare it to
that of the same flexible chain in a bath of hard, thermal-like, vibrated
disks. We demonstrate experimentally that the mean length and mean radius of
gyration of both chains obey Flory's Law. However, the Kuhn length associated
with the number of correlated monomers is smaller in the case of the active
bath, corresponding to a higher effective temperature. Importantly, the active
bath does not just simply map on a hot equilibrium bath. Close examination of
the chains' configurations indicates a marked bias, with the chain in the
active bath more likely assuming configurations with a single prominent bend.
