We present a color analysis of the galaxy populations of candidate clusters of galaxies from the Palomar Distant Cluster Survey [Postman et at., AJ, 111,615(1996)]. The survey was conducted in two broad band filters that closely match V and I and contains a total of 79 candidate clusters of galaxies, covering an estimated redshift range 0.2<~ z <~ 1.2. We examine the color evolution in the 57 richest clusters from this survey, the largest statistical sample of distant clusters to date. The intermediate redshift (0.2 < z < 0.4) clusters show a distinct locus of galaxy colors in the color-magnitude diagram. This ridge line corresponds well with the expected no-evolution color of present-day elliptical galaxies at these redshifts. In clusters at redshifts of z >~ 0.5, this red envelope has shifted bluewards compared to the ``no-evolution" prediction. By z ~ 0.8 there are only a few galaxies which are as red in their rest-frame as present-day ellipticals, consistent with recent claims on the basis of optical-infrared colors. The detected evolution is consistent with passive aging of stellar populations formed at redshifts of z ~> 2. Though the uncertainties are large, the Butcher-Oemler effect is observed in the Palomar clusters. The fraction of blue galaxies increases with the estimated redshift of the cluster at a 96.2% confidence level. The measured blue fractions of the intermediate redshift clusters (f_b_ ~ 0.2-0.3) are consistent with those found previously by Butcher & Oemler [ApJ, 285,426 (1984)]. The trend in the Palomar clusters suggests that f_b_ can be greater than 0.4 in clusters of galaxies at redshifts of z ~> 0.6.
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Lori M. Lubin (1996) studied this question.