*Pathological Reactions. Derivatives of Stimulus Words.*--We place here any reaction which is a grammatical variant or derivative of a stimulus word. The tendency to give such reactions seems to be dependent upon a suspension or inhibition of the normal process by which the stimulus word excites the production of a new concept, for we have here not a production of a new concept but a mere change in the form of the stimulus word. As examples of such reactions may be mentioned: _eating--eatables_, _short--shortness_, _sweet--sweetened_, _quiet--quietness_. *Partial Dissociation.*--We have employed the term dissociation to indicate a rupture of that bond--whatever be its nature-which may be supposed to exist normally between stimulus and reaction and which causes normal persons to respond in the majority of instances by common reactions. And we speak of partial dissociation where there is still an obvious, though weak and superficial, connection. Under this heading we can differentiate four types: *Non-specific Reactions* have already been defined; we distinguish those in this class from those in the class of common reactions by means of the frequency tables. *Sound Reactions.*--This type requires no explanation; the main difficulty is to decide what degree of sound similarity between stimulus and reaction should be deemed sufficient for placing a reaction under this heading. The total number of different sounds used in language articulation is, of course, small, so that any two words are liable to present considerable chance similarity. Some time ago we estimated the average degree of sound similarity between stimulus words and reaction words in a series of one hundred test records obtained from normal persons; we found that on the average 14.53 per cent of the sounds of the stimulus words were reproduced, in the same order, in the reaction word. Our experience finally led us to adopt the following general rule: A reaction is to be placed under this heading when fifty per cent of the sounds of the shorter word of the pair are identical with sounds of the longer word and are ranged in the same order. Among sound reactions we occasionally find *neologisms*; for these a separate heading is provided. Possibly their occurrence may be taken as an indication of an exaggerated tendency to respond by sound reactions. *Word Compliments.*--Here we include any reaction which, added to the stimulus word, forms a word, a proper name, or a compound word in common use. *Particles of Speech.*--Under this heading we include articles, numerals, pronouns, auxiliary verbs, adverbs of time, place and degree, conjunctions, prepositions, and interjections.