In the early part of this century, Henry Head and his collaborators published a notable series of papers on altered somatic sensation after lesions at various levels of the nervous system (Head, 1920). These papers are a landmark in the history of sensory neuropsychology and provide a wealth of careful observations woven into a comprehensive, evolutionary theory. Although the meager anatomical and physiological knowledge available to Head led to serious errors in this theory, some of the ideas expressed continue to be influential. Indeed, during the last decade, 143one of Head’s conceptions has received attention and favorable comment from leading anatomists and physiologists (Herrick & Bishop, 1958; Lele & Weddell, 1959; Nauta & Kuypers, 1958; Rose & Mountcastle, 1959). This conception is that the somatosensory apparatus is divisible, morphologically and functionally, into protopathic and epicritic components.