The problem of this investigation might appear to be a matter of concern primarily for the geneticist. None the less, it is also one of very great interest to th» psychologist. For could we, as geneticists, discover the complete genetic mechanism of a character such as maze-learning ability-i.e., how many genes it involves, how these segregate, what their linkages are, etc.-we would necessarily, at the same time, be discovering what psychologically, or behavioristically, maze-learning ability may be said to be made up of, what component abilities it contains, whether these vary independently of one another, what their relations are to other measurable abilities, as, say, sensory discrimination, nervousness, etc. The answers to the genetic problem require the answers to the psychological, while at the same time the answers to the former point the way to those to the latter. But as far as the present investigation is concerned it must be admitted that only the most elementary answers of either sort have as yet been obtained. The preliminary problems of technique and method of attack have proved all important. 1 The present paper is in the nature of a first report upon a relatively extensive program which is being worked on in this laboratory. The original impetus which started the problem came from Prof. Warner Brown; and most of the actual labor has been and is being performed by others beside the writer. In particular, it was only through the very exceptional industry and persevering labor of Mr. Frederick J. Adams that most of the 300 odd maze records here reported were obtained. To Prof. Raymond Franzen, the writer owes great indebtedness for suggestions as to the statistical treatment of the results. And the actual .computations involved were in large part performed and supervised by Miss Barbara Burks. The writer wishes also to acknowledge the receipt of 3 grants from the Research Board of this University amounting in all to $540. COHPARAXIVI PSYCHOLOGY, VOL. IV, NO. 1 * Zero correlations have since been found for time, for one set of animals in two successive mazes (3).