<p>While the cells of living things are liq.-cultured in an incubation tank, part of the culture soln. is filtrated and taken out using a hydrophobic filter membrane. The filter membrane is intermittently back-washed by the culture soln. Clogging of the filter membrane is prevented and sepn. and concn. of the cells is made efficiently. A defoaming layer made of a water-repellent material is located on the surface of the culture soln. to rupture foams and bubbles generated by the gas blown out from a nozzle in the incubation tank.</p>
