DOES THE NUMBER DENSITY OF ELLIPTIC GALAXIES CHANGE AT Z-LESS-THAN-1

We have performed a detailed V/V-max test for a sample of the Canada-F rance Redshift Survey (CFRS) for the purpose of examining whether the comoving number density of field galaxies changes significantly at red shifts of z < 1. Taking into account the luminosity evolution of galax ies, which depends on their morphological type through different histo ries of star formation, we obtain [V/V-max] approximate to 0.5 in the range of 0.3 < z < 0.8. where reliable redshifts were secured by spect roscopy of either absorption or emission lines for the CFRS sample. Th is indicates that a picture of mild evolution of field galaxies withou t significant mergers is consistent with the CFRS data. Early-type gal axies, selected by their (V - I)(AB) color, become unnaturally deficie nt in number at z > 0.8 as a result of the selection bias, thereby cau sing a fictitious decrease of [V/V-max]. We therefore conclude that a reasonable choice of upper bound of redshift z similar to 0.8 in the V /V-max test saves the picture of the passive evolution of field ellipt ical galaxies in the CFRS sample, which was rejected by Kauffmann, Cha rlot, & White without confining the redshift range. However, about 10% of the CFRS sample consists of galaxies that have colors that are muc h bluer than predicted for irregular galaxies, and their [V/V-max] is significantly larger than 0.5. We discuss this population of extremely blue galaxies in terms of starbursting that has just turned on at the ir observed redshifts.