Dementia præcox 108 cases. Paranoic conditions 33 " Epilepsy 24 " General Paresis 32 " Manic-depressive insanity 32 " Involuntary melancholia 8 " Alcoholic psychoses 6 " Senile dementia 4 " A comparison of our pathological with our normal material _en masse_ reveals in the former evidence of a weakening of the normal tendency to respond by common reactions. This is shown in Table II. TABLE II. Common Doubtful Individual reactions. reactions. reactions. 1,000 normal subject 91.7% 1.5% 6.8% 247 insane subjects 70.7% 2.5% 26.8% It seems evident from this that pathological significance attaches mainly to individual reactions, so that our study resolves itself largely into (1) an analysis and classification of individual reactions and (2) an attempt to determine what relationship, if any, exists between the different types of reactions and the different clinical forms of mental disease. § 2. CLASSIFICATION OF REACTIONS. Those who have attempted to use the association test in the study of insanity have felt the need of a practical classification of reactions, and have at the same time encountered the difficulty of establishing definite criteria for distinguishing the different groups from one another. It is a comparatively simple matter to make these distinctions in a general way and even to formulate a more or less comprehensive theoretical classification, but there still remains much difficulty in practice. We have made repeated attempts to utilize various systems of classification which involve free play of personal equation in their application. Although for us the matter is greatly simplified by the elimination of all the common reactions with the aid of the frequency tables, we have nevertheless met with no success. The distinctions made by either of us have on no occasion fully satisfied, at the second reading, either the one who made them or the other, while a comparison of the distinctions made by each of us independently has shown a disagreement to the extent of 20-35 per cent.