Electron microscopical observations were made on exudates obtained from plants of Bidrus pilosa, Chenopodium amaranticolor Leonolis nepaetifolia, Helianthus annums. Nicotiana tabucum, Cassia occidentalis, Chenopodium ambrosioides, and Physalis floridona infected with a virus that induces mosaic on the first named species. The presenes of a flexible thread with a normal length 720 mm. x 12-13 mm was recorded in the exudates from the: diseased plants, but not in those from the healthy ones, and is considered to represent the causal virus.