Bodies thought to be equivalent to the phragmosomes described by Porter and Caulfield in Onion root tips have been demonstrated in the cytoplasm of Equisetum (mother cell), Pinns (embryo), and Anthoceros (capsule meristem). Their behaviour during stages of mitosis from metaphase to telophase has been traced in Anthoceros and they have been shown to persist and perhaps to increase after mitotic growth has ceased. Though commonly associated in a characteristic way with the spindle and cell plate, there is no positive evidence in favour of a causal connexion with either. Bipartition of individual phragmosomes occurs in relation to the equatorial plane of the spindle but multiplication may also occur in other ways at other times. No function can yet be assigned to them nor has a developmental sequence been traceable between phragmosomes and any other cell component. They are therefore provisionally regarded as organelles sui generis.