In previous articles one of us1has emphasized that in most cases of vesical atony it is extremely difficult and often impossible to state with accuracy whether the vesical dysfunction is a result of primary neurogenic atony, neurogenic atony complicated by obstruction of the vesical neck or myogenic atony secondary to obstruction of the vesical neck. By means of illustrative cases in these previous papers it was shown that even though the most careful cystoscopic, cystometric and neurologic examinations are performed they often fail entirely to supply the correct answer to this diagnostic problem. It was brought out also that the etiologic differentiation of these conditions may be relatively unimportant as far as treatment is concerned. This subject assumes considerable importance when patients who are suffering from tabes dorsalis are concerned. The classic description of the pathologic changes found in this disease are "chronic inflammation of the posterior spinal