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! A full discussion would lead us to the conclusion that dextrality is due to a difference in development in the two hemispheres of the brain, that these differences are hereditary, and that they show themselves toward the end of the first year.
It is a singular circumstance that right-handedness and speech are controlled by the same hemisphere of the brain and from contiguous areas.

It would explain this--and at the same time it seems probable from other considerations--if we found that right-handedness was first used for expression before speech; and that speech has arisen from the setting aside, for further development, of the area in the brain first used for right-handedness.