In our work the best procedure for removing substances causing nonspecific staining in order to obtain specific conjugates was to pass the conjugates through a DEAE-cellulose column and in some cases to absorb the first and second milliliter fractions with sweet clover tissue powder.

The specific staining by both direct and indirect methods showed that WTV antigen was concentrated in the pseudophloem tissue and in a few thick walled cells in the xylem region, but was not detectable in any other tissues of the root and stem tumors. A study of the distribution of WTV antigen within the pseudophloem cells indicates that it is irregularly distributed in the cytoplasm.

Wound tumor virus is a leafhopper transmitted virus not easily transmissible by mechanical inoculation (Black, 1944; Brakke et al., 1954). The concentration and apparent localization of the WTV antigen in pseudophloem tissue of the tumor may indicate that the virus preferentially multiplies in the phloem and may need to be directly placed in this tissue in order to infect plants.