The Bigelow Laboratory for Ocean Sciences will acquire a modern flow cytometer for marine biology and oceanographic investigations. Flow cytometers have proven to be effective tools for ocean science research. Within a cytometer, a stream of bacteria, phytoplankton cells, or other microscopic particles is passed through a laser light beam. Different cells and particles can be automatically enumerated and classified according to how they fluoresce or react in response to the laser light. Analysis of the fluoresced signal can yield important information on cell size, cellular constituents, and metabolic condition. The new cytometer will be portable so it can be used at sea with fresh samples. It will also be available for use by guest investigators.