Dr. Bastian, when commenting in his _Brain as an Organ of Mind_ on the specific location of the cerebral function of articulate speech in the third left convolution of the brain, remarks: “It has been thought that a certain more forward condition of development of the left hemisphere--as a result of hereditary right-handedness recurring through generation after generation,--might gradually become sufficient to cause the left hemisphere to take the lead in the production of speech-movements. Some little evidence exists, though at present it is very small, to show that it is left-handed people more especially who may become aphasic by a lesion of the right third frontal gyrus.” Dr. Bastian further assumes it to be indisputable that the greater preponderance of right-hand movements in ordinary individuals must tend to produce a more complex organisation of the left than of the right hemisphere; and this both in its sensory and motor regions. With the left-handed, however, so many motives are constantly at work tending to call the right hand into play, that the compensating influences must in their case tend to check any inequality in the development of the two hemispheres; so that there would seem rather to be a probability in favour of a more equable, and consequently healthful development of both cerebral hemispheres in the left-handed, but really ambidextrous manipulator. But it is to be noted that while Dr. Bastian recognises a correlation between the development of one or other cerebral hemisphere and the greater dexterity of the opposite hand, he is inclined to recognise right or left-handedness as the cause rather than the effect.