Changes in the Lipids of Cells from Aging Populations of Tetrahymena pyriformis*†

SYNOPSIS. Lipids in aging cultures of Tetrakymena pyriformis were extracted at various times after inoculation, purified, and weighed or chromatographed on thin layers of silica gel. The total cellular lipid increased throughout logarithmic and early stationary phases but decreased sharply after 72 hr. The amount of one lipid class, probably the triglycerides, followed the same trends. It may be a cellular reserve.