It was not possible, in 1800, to go further, or to put the facts of reflex action more clearly: but this fine sentence gives no hint of the truth that guided Marshall Hall--that the "consent and commerce" of reflex action are to be found at definite points or levels in the spinal cord; that the cord no more "works as a whole" than the brain. The greatness of Marshall Hall's work lies in his recognition of the divisional action of the cord: he proved the existence of definite centres in it, he discovered the facts of spinal localisation, and thus foreshadowed the discovery of cerebral localisation. In his earlier writings (1823-33) he showed how the movements of the trunk and of the limbs are only one sort of reflex action; how the larynx, the pharynx, and the sphincter muscles, all act by the "consent and commerce" of the spinal cord. Later, in 1837, he demonstrated the course of nerve-impulses along the cord from one level to another, the results of direct stimulation of the cord, and other facts of spinal localisation. He noted the different effects of opium and of strychnine on reflex action; and he extended the doctrines of reflex action beyond physiology to the convulsive movements of the body in certain diseases. 3. _Flourens_ (1794-1867) Beside his work on the nervous system, Flourens studied the periosteal growth of bone, and the action of chloroform;[7] but he is best known by his experiments on the respiratory centre and the cerebellum. The men who interpreted the nervous system followed the anatomical course of that system: first the nerve-roots, then the cord, then the medulla oblongata and the cerebellum, and last the cerebral hemispheres; a steady upward advance, from the observation of decapitated insects to the localisation of centres in the human brain. Flourens, by his work on the medulla oblongata, localised the respiratory centre, the nerve-cells for the reflex movements of respiration:-- "M. Flourens a circonscrit ce centre avec une scrupuleuse précision, et lui a donné le nom de noeud vital" (Cl. Bernard.) [7] When Flourens died, Claude Bernard was appointed to his place in the French Academy; and, in the _Discours de Reception_ (May 27, 1869), said, "It is twenty-two years since the discovery of anæsthesia by ether came to us from the New World, and spread rapidly over Europe. M. Flourens was the first man who showed that chloroform is more active than ether."