A Note on Vessel Structure in the Xylem of Roots of M.XVI Apple Rootstock

A strain of arabis mosaic virus, introduced in unsterilized compost, caused severe disease and complete loss of crop in cucumbers under glass. The virus was transmitted by sap inoculation to 42 out of 73 plant species. Infected Nicotiana clevelandii plants were freed from the virus when grown at 38° C. for three weeks. Although closely related serologically to isolates of arabis mosaic from raspberry and Sambucus nigra, the cucumber isolate did not protect some plants against the Sambucus isolate. Purified virus preparations contained “ spherical ” particles about 30 mμ diameter, and produced specific light-scattering zones in density-gradient centrifugation.