  We present deep spectroscopic and imaging data of the host galaxies of Mrk
1014, IRAS 07598+6508, and Mrk 231. These objects form part of both the QSO and
the ultraluminous infrared galaxy (ULIG) families, and may represent a
transition stage in an evolutionary scenario. Our imaging shows that all three
objects have highly perturbed hosts with tidal tails and destroyed disks, and
appear to be in the final stages of major mergers. The host galaxies of the
three objects have spectra typical of E+A galaxies, showing simultaneously
features from an old and a young stellar component. We model spectra from
different regions of the host galaxies using Bruzual & Charlot spectral
synthesis models using two component models including an old underlying
population and recent superposed starbursts. Our results indicate a strong
connection between interactions and vigorous bursts of star formation in these
objects. We propose that the starburst ages found are indicative of young ages
for the QSO activity. The young starburst ages found are also consistent with
the intermediate position of these objects in the far infrared color-color
diagram. (abridged)
