Warthin[188] at autopsy found evidences of active syphilis in a series of forty-one inactive or "cured" cases investigated by him. Eleven of these had been treated, were supposed to have recovered and showed no syphilitic manifestations at the time of death. Five had received an extended course of salvarsan therapy and in twenty-five there was no history of syphilis at all. Spirochaetes were demonstrated by the Levaditi method in thirty-six of the forty-one cases—in the aorta in thirty-two, in the testes in thirty-one, in the liver in four, in the adrenals in six, in the pancreas in six, in the spleen in one and in the nervous system in five. In some of these cases the Wassermann reaction was reported as negative. Warthin concluded that cured syphilis in many if not all instances is in a latent condition, spirochaetes of a low virulence still remaining active. For purposes of statistical study the American Psychiatric Association has not attempted any clinical differentiation of the various types of this disease, a procedure which was felt to be inadvisable at this time. The following suggestions appear in the manual as to the classification of psychoses due to cerebral syphilis:— "Since general paralysis itself is now known to be a parenchymatous form of brain syphilis, the differentiation of the cerebral syphilis cases might on theoretical grounds be regarded as less important than formerly. Practically, however, the separation of the non-parenchymatous forms is very important because the symptoms, the course and therapeutic outlook in most of these cases are different from those of general paralysis. "According to the predominant pathological characteristics, three types of cerebral syphilis may be distinguished, viz.: (a) Meningitic, (b) Endarteritic, and (c) Gummatous. The lines of demarcation between these types are not, however, sharp ones. We practically always find in the endarteritic and gummatous types a certain amount of meningitis. "The acute meningitic form is the most frequent type of cerebral syphilis and gives little trouble in diagnosis; many of these cases do not reach state hospitals. In most cases after prodromal symptoms (headache, dizziness, etc.) there is a rapid development of physical signs, usually cranial nerve involvement, and a mental picture of dulness or confusion with few psychotic symptoms except those related to a delirious or organic reaction. "In the rarer chronic meningitic forms which are apt to occur a long time after the syphilitic infection, usually in the period in which we might expect general paralysis, the diagnostic difficulties may be considerable. "In the endarteritic forms the most characteristic symptoms are those resulting from focal vascular lesions. "In the gummatous forms the slowly developing focal and pressure symptoms are most significant.