A Centrifuge for Rapid Concentration of Large Fragile Cells Without Extensive Lysis*

SYNOPSIS. When large batches of Paramecium (more than 100,000 cells) are centrifuged in conventional centrifuges, extensive lysis occurs, typically lowering recovery to around 30%. An easily constructed centrifuge with a cylindrical plastic head operated at low accelerations permits centrifugation of large batches of Paramecium with about 90% recovery, even after exhaustive washing. Operation requires only a few minutes, and the system is easily cleaned. The inexpensive heads can be instantly interchanged, and cultures can even be centrifuged in their original low form glass culture vessels. This system, which should be applicable to any large fragile cells, permits timed experiments that are usually impossible because of the need for exhaustive washing or concentration from large initial volumes.