ml of the suspension was retained in a 3l spinner bottle and 3 500 ml of fresh medium was added the total of 16l of suspension was returned to the 37 u00b0 c room for 96 hours f after a total of 264 hours in suspension culture the sv3t3 cells were again examined microscopically there were very few less than 5 dye permeable cells and the cellular cytoplasm had lost its granular appearance the cells were growing in clumps up to 0 02 mm in diameter while smaller aggregates of 2 3 4 or more cells were also visible the 3l spinner cell suspension was transferred to a 12l spinner bottle with addition of fresh medium the 12l spinner cell suspension was split into 4 new 12l spinners with the addition of fresh medium all of these were set up with 5 co 2 in air in addition a 1l non gassed spinner bottle and a 3l gassed spinner bottle were used to maintain the culture all spinner bottles were returned to the 37 u00b0 c room for 72 hours g one of the 12l spinner bottles had samples removed every 24 hours for dna determinations see the table below and 1l of the cell suspension was removed and the cells were frozen in liquid n 2 fig1 and 2 show photomicrographs made of the suspension culture of cells at 312 hours after initiation of the culture in suspension taken at about 30x magnification in particular fig1 shows a relatively large clump of cells while fig2 shows several smaller clumps of.