  The spectral properties of more than 400 CFRS galaxies and their changes over
the redshift interval 0 - 1.3 are investigated. Emission line intensities and
equivalent widths for accessible lines have been measured, as well as continuum
color indices based on 200A wide spectral regions. Within the CFRS sample, the
comoving fraction of galaxies with significant emission lines (EW(OII) > 15A)
increases from ~13% locally to over 50% at z > 0.5. The fraction of luminous (
M_{B} < -20) quiescent galaxies (those without [OII] 3727 emission) decreases
with redshift from 53% at z = 0.3 to 23% at z > 0.5, the latter fraction being
similar to that of early type galaxies at that redshift. There is considerable
evidence in the data presented here that star formation increases from z = 0 to
z > 0.5 in disk galaxies. However, the absence of extremely blue colors and the
presence of significant Balmer absorption suggests that the star formation is
primarily taking place over long periods of time, rather than in
short-duration, high-amplitude ``bursts''. There are several indications that
the average metallicity and dust opacity were lower in emission-line galaxies
at high redshift than those typically seen in luminous galaxies locally. Beyond
z = 0.7, almost all the emission-line galaxies, including the most luminous (at
1mu at rest) ones, have colors approaching those of present-day irregular
galaxies, and a third of them have indications (primarily from the strength of
the 4000A break) of metallicities significantly less than solar (Z < 0.2
Z_{sun}). (abbreviated)

Astrophysics