myasthenia by the clinician. From this sprang thymec-tomy and the observations of pharmacologists and physiologists on a possible relationship between the thymus gland and the myoneural junction. Essential though the contributions of the non-clinical scientists are to the solution of the problem, I do not believe that the work of the clinical neurologist is therefore finished. Looking broadly at the clinical picture he may well ask himself whether myasthenia is a single entity-whether in fact it is a disease or a symptom; whether there is such a thing as thyrotoxic myasthenia as well as an association between thyrotoxicosis and myasthenia gravis, and where in the picture are to be placed the myasthenic syndromes associated with avitaminosis and with carcinoma of the lung. In other words the contributions which the pathologist and the biochemist are making to the building up of the hypothesis about myasthenia should stimulate the clinician to discriminate further in his own field.