THE DNA-REPLICATION CYCLE DURING CHROMOSOME POLYTENIZATION IN THE SALIVARY-GLAND CELLS OF CHIRONOMUS-THUMMI .4. THE DURATION OF S-PHASE OF DIPLOID-CELLS

The level of ploidy and the cell cycle duration of the imaginal discs cells of Chironomus larvae of the 5th phase of the IVth instar were studied. The imaginal discs of the leg in the first thoracic segment of larvae were used. By cytophotometry it was shown that the majority of cells in the leg discs were diploid. By autoradiography it was determined that the duration of the cell cycle of the leg discs cells was 39h, with t(G1), t(S), t(G2) and t(M) equal to 23, 10, 5 and 1h, respectively.