The Presidential Address by Prof. Hopwood was the terminal event of the scientific proceedings of the Congress, and was delivered before a large audience at the Central Hall, Westminster, on Friday afternoon, December 9. It was accompanied by lantern slides, and followed by a cinematograph demonstration.Prof. Hopwood said that every congress he had attended had organised some excursion for its members, and he proposed to take the audience on an excursion along the new arterial road which has been driven right through science and medicine, the road of radiation.[The President here showed the electro-magnetic spectrum, indicating the different classes of radiation, from the longest to the shortest waves.]He then showed examples of recent research in various fields of radiological interest, commencing with a record of experiments carried out by Prof. Bose in the Bose Institute at Calcutta. These experiments related to the effect of short wireless waves on the growing wheat plant. When a strong wireless signal was received by the plant, the plant showed a retardation in growth. Less strong signals showed a retardation of growth followed by growth stimulation, while weak signals were followed by stimulation only. There is a lag of two or three seconds between the transmission of the stimulus and the effect produced.