Increase in dry mass of Ehrlich ascites tumor cells after treatment with nitrogen mustard.

The increase in mean dry mass per cell in the surviving population of the Ehrlieh aseites tunmr cells after t rea tment with I IN~ was studied with the aid of the interference microscope. The carcinoma cells in animals t reated with a single dose (~.5 mg/kg) of HN~ 5 days after tumor t ransplant showed no change in mean dry mass during the first 8 hours after t reatment . Start ing soInetime between the 8th and the o~4th hour, the mean dry mass per cell increased at a uniform rate of about ~50 arbi t rary units every 80 hours for five of the six treated animals and about ~,5 arbi t rary unit.s every 18 hours for the sixth animal, in spite of the suppression of mitotic indices from the 3d hour to the 6th day posttreatment . Control alfimals showed no significant change in either dry mass values or mitotic index.