REPLICATION OF DNA AND CELL DIVISION IN SYNCHRONOUSLY DIVIDING CULTURES OF EUGLENA GRACILIS.

Autotrophic Euglena gracilis Klebs (strain Z) that are grown axenically on defined, inorganic medium on a regime of 14 hours of light and 10 hours of darkness double their cell number every 24 hours by dividing synchronously during the dark period. The DNA content doubles in a stepwise manner during the last 6 hours of the light period just prior to cell division. This result agrees with those for most higher cells. Although DNA replication is a necessary condition for cell division it is not a sufficient one.