Studies on the Growth of Human Carcinoma Cells in Tissue Culture* CHARLESG. SMITH,WILLIAML. LUMMIS,ANDJOSEPHE. GRADY

serum. The maximum cell concentration was a function of the frequency of medium renewal, the time of incubation, and the amount of final cellular material present. Maximum cell density could be increased approximately twofold by the addition of various peptones to the complete medium, although these materials did not affect the minimum generation time. Fortification of the medium with glucose, glutamine, or vitamin mixture did not prolong the growth phase or affect the generation time. When complete medium was incubated for 8 days at 37° C., it was found to be fully