The preparation of a new set of statistical tables by the Medico-Psychological Association of Great Britain and Ireland for the annual recording of the vast clinical and pathological data and returns of all public asylums in the future has brought forward the inevitable question of the nomenclature and classification of the insanities. Dr. C. A. Mercier, in an article in the Journal of Mental Science for January, deals with the “kinds of insanity” which he thinks fulfil the necessary conditions of true diseases. The arrangement suggested is first to separate congenital from non-congenital cases of insanity. The congenital cases would include all idiots and most imbeciles. The classification of these is a matter of subordinate importance, whereas the division of the insanities proper into natural groups is the main desideratum in mental science and the most important aid to clearness of thought of diagnosis, and of prognosis. Cases of insanity are proposed to be considered in one of two classes – viz., general paralysis (paralytic dementia) and non-paralytic insanity. Dr. Mercier suggests that the latter class contains “diseases sufficiently distinct that merit the same separation that is given to general paralysis.... As to general paralysis the symptoms are so distinct that it is recognisable at every stage in its progress. It has a definite history, runs a definite course, and forms a complete clinical picture separable from that of any other form of insanity.” Examining other varieties of insanity and their titles or claims to be called diseases, Dr. Mercier would admit “acute delirious mania” owing to its characteristic symptoms and its course as a definite variety of insanity. “The clinical picture of acute delirious mania is distinct and prevents it from being confused with any other type of insanity. On the contrary,” he says, “puerperal insanity presents us with no distinct clinical picture. The very fact that it has been divided into puerperal mania and puerperal melancholia is proof of what I say. Puerperal insanity is acute insanity occurring within an uncertain time of childbirth, and if the antecedent of childbirth is disregarded there is nothing whatever in the clinical picture of the disease that is different from other causes of acute insanity that have no connexion with the puerperium or even in acute insanity occurring in men.” The insanity of pregnancy is regarded as having a much better right to be considered a disease, “for the fact of pregnancy is a continuing feature in the clinical picture, a feature which at once marks off the case from all other cases of insanity.” What is true of the insanity of pregnancy, he adds, is emphatically true of the insanity of lactation. It is an insanity of exhaustion – of innutrition – and differs in no respect from other cases of insanity of similar origin. Few cases of insanity occurring at the menopause in women deserve recognition as a separate variety of insanity. Similar cases may occur at other times of life and present the same clinical picture. The definite form of insanity of the menopause “with its special facies” is, says Dr. Mercier, rare. Senile insanity has no right to a special place in nosology. “The term means, it appears, insanity not assigned to any distinct category except by its occurrence in advanced age. It would, in my opinion, be unreasonable to base the differentia of the disease on so slender a foundation.” The insanity of epilepsy is admitted to have “a good title to the denomination of a disease.” Cases of insanity associated with bodily diseases, whether the latter be regarded as a cause or not, in no case present a clinical picture of sufficient distinctness to entitle them to separate rank as diseases. Dr. Mercier would admit the claims of a stupor, paranoia, recurrent and alternating insanity, and the two forms of insanity occurring in adolescents or young adults known as hebephrenia and katatonia. Causes of fixed delusion would also find a place in classification, being further subdivided as the delusions are persecutory, exalted, and personal. Alcoholic insanity would be recognised in its subdivisions of mania a potu, delirium tremens (acute forms), or alcoholic insanity proper of the chronic form. This threefold subdivision of alcoholic insanity would exclude all cases in which alcohol was not the main actuating cause of the malady. The above-named varieties of insanity, concluded Dr. Mercier, “have claim to the title of distinct diseases from the distinct clinical pictures they present; all other cases must be lumped together under the heading of insanity simpliciter.”