Indonesian studying in New Zealand. Mr Mohamad Mahfoedi, from the Government Bureau of Horticulture, Java, Indonesia, at Lincoln Agricultural College, near Christchurch, New Zealand, where he is undertaking a course in potato breeding under a Colombo Plan traineeship. He is here testing a potato variety to see whether it is infected with virus. He takes a leaf of the potato, grinds it up and rubs some of the sap on to the test plants, which, within 8 to 15 days will show definite symptoms if virus is present. The method is called “testing by sap inoculation”.