ALL the facts were compatible with the view that the two substances detected in this work were acetyl choline and adrenaline, but Loewi was too cautious to jump to this conclusion. In 1929 Dale and Dudley, working with large-scale apparatus, isolated acetylcholine for the first time from animal tissues, and came to the conclusion that vagusstoff could now be definitely identified as acetylcholine. New evidence has justified this conclusion. The pharmacological methods for identifying small quantities of acetylcholine were improved in Dale's laboratory until it was possible to distinguish acetylcholine from such nearly related substances as propionylcholine, and, with these improved methods, it was shown that a substance which could be definitely identified as acetylcholine was liberated, not only by nerves with muscarine-actions, but also by nerves with nicotine-actions. This year, Loewi, working with a method developed in Dale's laboratory, has obtained evidence which enabled him to identify acceleransstoff as adrenaline. Though many have worked in this field, these two men have thus obtained all the vital evidence for the modern view that most, if not all, mammalian motor nerves produce their effects by the local liberation of either acetylcholine or adrenaline.