The effects of severance of the nerve to a muscle, whether accidentally in man or in experiments in animals, are striking enough. Besides the loss of power to move, except upon electrical stimulation, a state of atrophy with gradual wasting away of the fibres ensues. About the middle of last century there was much discussion about the need for special trophic nerves. S. Mayer (1) in Hermann's ‘Handbuch der Physiologie’ of 1879 considered this question at length and concluded that there was no proof of the existence of trophic nerves, but that in special cases (e.g. muscle and glands) the nerve supply was concerned in a trophic process of a special nature. Michael Foster (2) also, writing at this same time, was of the opinion that much of the effect of loss of nerve supply could be explained by absence of the usual functional activity. Nevertheless he expressed the view that ‘some more or less direct influence of the nervous system on metabolic actions, and so on nutrition, will be established by future inquiries.’ Langley (1, 2) some forty years later specifically studied the part played by lack of movement in atrophy after nerve section and found that neither passive movement nor active movement caused by electrical stimulation was effective in delaying atrophy. He emphasised however that denervated muscle may be in constant fibrillation, so that it remained possible that the atrophy was caused by fatigue.