1. I found no continued preference for either hand as long as there were no violent muscular exertions made (based on 2,187 systematic experiments in cases of free movement of hands near the body--i. e., right hand, 577 cases; left hand, 568 cases--a difference of 9 cases; both hands, 1,042 cases; the difference of 9 cases being too slight to have any meaning); the period covered being from the child's sixth to her tenth month inclusive. 2. Under the same conditions, the tendency to use both hands together was about double the tendency to use either (seen from the number of cases of the use of both hands in the figures given above). 3. A distinct preference for the right hand in violent efforts in reaching became noticeable in the seventh and eighth months. Experiments during the eighth month on this cue gave, in 80 cases, right hand, 74 cases; left hand, 5 cases; both hands, 1 case. This was true in two very distinct classes of cases: first, reaching for objects, neutral as regards colour (newspaper, etc.), at more than the reaching distance; and, second, reaching for bright colours at any distance. Under the stimulus of bright colours, from 86 cases, 84 were right-hand cases and 2 left-hand. Right-handedness had accordingly developed under pressure of muscular effort in the sixth and seventh months, and showed itself also under the influence of a strong colour stimulus to the eye. 4. Up to this time the child had not learned to stand or to creep; hence the development of one hand more than the other is not due to differences in weight between the two longitudinal halves of the body. As she had not learned to speak or to utter articulate sounds with much distinctness, we may say also that right or left-handedness may develop while the speech centres are not yet functioning. Further, the right hand is carried over after objects on the left side, showing that habit in reaching does not determine its use. _Theoretical_.--Some interesting points arise in connection with the interpretation of these facts. If it be true that the order of rise of mental and physiological functions is constant, then for this question the results obtained in the case of one child, if accurate, would hold for others apart from any absolute time determination. We should expect, therefore, that these results would be confirmed by experiments on other children, and this is the only way their correctness can be tested. If, when tested, they should be found correct, they would be sufficient answer to several of the theories of right-handedness heretofore urged, as has been already remarked. The rise of the phenomenon must be sought, therefore, in more deep-going facts of physiology than such theories supply. Furthermore, if we go lower in the animal scale than man, analogies for the kinds of experience which are urged as reasons for right-handedness are not present; animals do not carry their young, nor pat them to sleep, nor do animals shake hands!