Another theory maintains that the development of right-handedness is due to differences in weight of the two lateral halves of the body; this tends to bring more strain on one side than the other, and to give more exercise, and so more development, to that side. This evidently assumes that children are not right or left-handed before they learn to stand. This my results given below show to be false. Again, we are told that infants get right-handed by being placed on one side too much for sleep; this can be shown to have little force also when the precaution is taken to place the child alternately on its right and left sides for its sleeping periods. In the case of the child H., certain precautions were carefully enforced. She was never carried about in arms at all, never walked with when crying or sleepless; she was frequently turned over in her sleep; she was not allowed to balance herself on her feet until a later period than that covered by the experiments. Thus the conditions of the rise of the right-handed era were made as simple and uniform as possible. The experiments included, besides reaching for colours, a great many of reaching for other objects, at longer and shorter distances, and in unsymmetrical directions. I give some details of the results of the experiments in which simple objects were used, extending over a period of four months, from the fifth to the ninth in her life. The number of experiments at each sitting varied from ten to forty, the position of the child being reversed as to light from windows, position of observation, etc., after half of each series. No trace of preference for either hand was discernible during this period; indeed, the neutrality was as complete as if it had been arranged beforehand, or had followed the throwing of dice. I then conceived the idea that possibly a severer distance test might affect the result and show a marked preferential response by one hand over the other. I accordingly continued to use a neutral stimulus, but placed it from twelve to fifteen inches away from the child. This resulted in very hard straining on her part, with all the signs of physical effort (explosive breathing sounds resulting from the setting of the larynx, rush of blood to the head, seen in the flushing of the face, etc.). The number of experiments in each series was intentionally made very small, from one to twelve, in order to avoid fatigue.