Membranous sacs associated with cilia of Paramecium

A membranous system associated with the cortical cilia of Paramecium putrinum is described. A sac lies below the cortical kinetosomes and extensions from it pass along the kinetodesmal fibre to lie near, or make contact with, the parsomal sac and also pass deep into the cytoplasm to pass close to a mitochondrion. Because of its widespread occurrence in this and other species it is suggested that the system plays a physiologically active role.