SUMMARY.In this paper the symptoms of aucuba mosaic of tomato in.N. glutinosaare described. A method is discussed whereby it is possible to count the spots formed after inoculation with juice diluted to different strengths. The fact that the number of spots formed is proportional to the amount of dilution is taken as indication of the particulate nature of the virus. A method is suggested for counting the number of virus particles present in a juice. It is shown that the amount of virus present in a juice does not increase after agitation or after treatment with proteolytic enzymes. With trypsin and diastase they were decreased. This decrease, it is suggested, is due to the adsorption rather than to the destruction of the virus. The amount of multiplication of the virus in the tissues ofN. glutinosais examined and compared with the much greater multiplication in tomato tissues.This work was carried out under the auspices of the Empire Marketing Board.