Following identification in 1932 of the Yellow-edge virus disease in England on the Royal Sovereign variety, "normal" plants of this variety from a clone minutely rogued for Yellow-edge were used at St. Catharines as indicators in a further study of virus as relating to certain Ontario varieties. Observations in the field and greenhouse, confined largely to the varieties Parson's Beauty, Premier (Howard 17), Forward and Glen Mary, showed that symptoms analogous to those of Yellow-edge in England and sufficiently defined to permit of diagnosis were apparent only on Parson's Beauty and Forward, and then only for a limited period early in the growing season. In the 1933–35 transmission experiments (by runner grafting), symptoms macroscopically indistinguishable from those of typical Yellow-edge-infected plants in England were induced on Royal Sovereign from the local varieties Glen Mary, Parson's Beauty and Premier, which possess markedly the symptomless-carrier capacity. Of special interest was the deterioration of Premier components in certain graft series, the evidence suggesting reciprocal infection between test and indicator plants.Finally, parallel experiments at the East Mailing Station in 1935–36 provided supplementary data as follows: (1) Of the two parent Fragaria species common to commercial varieties in North America and in England, F. chiloensis was found to be a symptomless-carrier of Yellow-edge with a high order of resistance, and F. virginiana, in complete contrast, exhibited symptoms with extreme readiness together with high susceptibility, thus providing some explanation of the observed wide range of varietal reaction to disease of the Yellow-edge type. (2) A large proportion of the clone of Royal Sovereign plants used as "normal" indicators in the recent series of experiments, was found to be infected with a distinct virus of the "Crinkle" type, thus providing explanation of an observed reciprocal reaction in certain series with the Premier variety.