placing of the hand over the heart is universally understood to signify love and fidelity. Uneducated deaf mutes, whose only means of communicating with their fellow-men is by gestures, not only use this sign, but imply hatred also by holding the hand over the heart accompanied by the sign of negation. Moreover, pointing to the heart accompanied by a cry of pain or joy would indicate respectively death of an enemy or friend. Again, primitive man protected himself from the weapons of his enemies by holding the shield in his left hand, thus covering the heart and leaving the right hand free to wield his spear. The question whether it would have been to his advantage to use either hand indifferently for spear and shield has been, to my mind, solved by the fact that in the long procession of ages evolution has determined right-handed specialisation as being more advantageous to the progress of mankind than ambidexterity. Right-handedness is an inherited character in the same sense as the potential power of speech. LOCALISATION OF SPEECH CENTRES IN THE BRAIN In 1863 Broca showed the importance in all right-handed people (that is in about ninety-five per cent of all human beings) of the third _left_ frontal convolution for speech (_vide_ figs. 16 and 17); when this is destroyed by disease, although the patient can understand what is said and can understand written and printed language, the power of articulate speech is lost. _Motor Aphasia_. This portion of the brain is concerned with the revival of the motor images, and has been termed by Dr. Bastian "the glosso-kinæsthetic centre," or the cortical grey matter, in which the images of the sense of movement of the lips and tongue are formed (_vide_ fig. 17). A destruction of a similar portion of the cortex in a right-handed person produces no loss of speech; but if the person is left-handed there is aphasia, because he, being left-handed, uses the third _right_ inferior frontal convolution for speech. These facts have for long been accepted by most neurologists, but recently doubts have been cast upon this fundamental principle of cerebral localisation by a most distinguished French neurologist, M. Marie; he has pointed out that a destructive lesion of the cortex may be accompanied by subcortical damage, which interrupts fibres coming from other parts of the brain connected with speech. In the study of speech defects it is useful to employ a diagram; a certain part of the brain corresponds to the _Speech Zone_ there indicated, and lesions injuring any part of this area in the left hemisphere cause speech defects (_vide_ fig. 17). All neurologists, M. Marie included, admit this, and the whole question therefore is: Is a destruction of certain limited regions of the superficial grey matter the cause of different forms of speech defects, or are they not due more to the destruction of subcortical systems of fibres, which lie beneath this cortical speech zone?