Abstract
Particles of maize mosaic virus I are bullet-shaped, or hemispherical at both ends. Bullet-shaped particles in phosphotungstic acid measure 2550 x 900 Å, those in uranyl acetate 2410 x 730 Å. The particles appear to consist of an envelope with thread-like or knob-like protrusions, a helical structure composed of beaded units, a hollow cylinder and an inner core. The last has no visible structure but disintegrates often in somewhat spherical masses.
* Some of the results were presented at the sixth Annual Meeting of the American Phytopathological Society, Caribbean Division, Maracay, Venezuela, 410 September, 1966.