Formal disturbances in thinking have been studied in schizophrenia (most notably by Bleuler) and in brain trauma (Kurt Goldstein and others), but their occurrence in delirium has received little attention.The basic thinking disturbance in delirium is disorientation. The special characteristics of delirious disorientation were explained by Hughlings Jackson, and I have considered them elsewhere.*This paper is divided into three sections. The third section deals with the inability of the delirious man to name the physician's vocation on command when he can name it spontaneously, a phenomenon of special interest from the standpoint of Jackson's views on neural function.DISTURBANCES OF ASSOCIATION This section deals with the disturbances of association which Bleuler demonstrated as one of the basic symptoms of schizophrenia. These disturbances are not confined to schizophrenia but occur in other psychoses as well. They abound in delirium, and the following cases are typical.Case 1.— Man aged