ELECTRON MICROSCOPY OF CYTOPLASMIC INCLUSIONS IN CELLS INFECTED WITH ROD-SHAPED VIRUSES

Thin sections of leaf tissue infected with 12 rod-shaped viruses varying from 180 mμ to 750 mμ in length were examined in the electron microscope. Neither intranuclear nor cytoplasmic inclusions occurred in healthy tissue. Intranuclear inclusions were observed only in material infected with tobacco etch virus. Several types of cytoplasmic inclusions were induced by the group of viruses varying in length from 730 mμ to 750 mμ; however, only one type of inclusion was common to all seven viruses of this group. It is proposed that this inclusion, which appears as a pin-wheel in cross section and as a bundle in longitudinal section, is diagnostic for infection with viruses of the potato Y group, i.e., rod-shaped viruses whose lengths vary from 730 mμ to 750 mμ.