Kennedy, in 1936, directed attention to allergy as a possible basis in the etiologic delineation of multiple sclerosis. He stated: "Its episodes, its remissions, the curability of its most acute crisis, its attack on the optic nerves, its neglect of sensory paths-all these things greatly resemble the happenings of localized allergic edemas after the central nervous system has come under fire. Further, the recent plaques in the rare autopsies of acute cases are not sclerotic; they are infiltrations by fluid of the nerve tissue surrounding blood vessels."
That same year Putnam pointed to the essential similarity between encephalomyelitis and multiple sclerosis. In 1941 he expressed the view that the origin of encephalomyelitis is in some sense an allergic reaction, adding that « it seems not unreasonable to suppose that an instability of the clotting mechanism of the blood might be one aspect of allergy. »