Cellulose Detected in the Stalk of Protostelium irregularis (Eumycetozoea)1

The stalk of Protostelium irregularis (Eumycetozoea) has been studied with light and electron microscopy and selected-area electron diffraction. The stalk is positively birefringent and fibrillar. Diffraction patterns obtained from stalks indicate that crystalline cellulose I is one component of the stalk.