(_i_) The height of a transverse localized lesion (_e.g._ a stab-wound) of one lateral half of the spinal cord is to be determined by the various groupings of symptoms stated in the preceding paragraphs, the chief guide being the limit-line between the sensitive and anæsthetic portions of the body, measured vertically. The symptoms are, however, distributed in a very remarkable manner on either side of the median line. The paralysis will be found on the same side as the lesion, often accompanied by hyperæsthesia, vaso-motor paralysis, and loss of muscular sense, while the anæsthesia is on the other side of the body. When such a lesion occurs below the first dorsal nerve, the symptom-group is designated as hemiparaplegia; when the lesion is higher up, so as to paralyze the arms, the affection is termed spinal hemiplegia (Brown-Séquard). Above the decussation of the pyramids total transverse lesions are practically unknown, so that the second question need not be followed farther. By means of the data above given we are also enabled to determine the length—_i.e._ fronto-caudal extension—of the systematic lesions of the cord. The symptoms of transverse lesions of the spinal cord are not exclusively caudad of the lesion, and some very striking ones are observable in the head. In lesions of the upper part of the dorsal cord and of the cervical enlargement (_e_, _f_, _g_) we observe vaso-motor and pupillary symptoms, due to injury of the spinal origin of the cervical sympathetic nerve; the pupils are contracted; the cheeks and ears congested and unnaturally warm; the cutaneous secretions are increased. In other words, the symptoms about the head, frontad of the lesion, are the same as those we produce experimentally in animals by section of the cervical sympathetic or of the lower cervical cord. In hemi-lesion of the cord, in man as in animals, these symptoms are unilateral, on the same side as the injury. Another point to be remembered in the study of transverse lesions of the spinal cord is that the lesion may involve enough of the anterior {77} gray horns to give rise to atrophic paralysis with De R. in some few muscles deriving their motor innervation from the focus of disease. This is not rarely seen in cervical paraplegia. THIRD QUESTION.—BEING GIVEN VERY LIMITED MOTOR OR SENSORY SYMPTOMS OF SPINAL ORIGIN, TO DETERMINE THE EXACT LOCATION OF THE FOCAL LESIONS CAUSING THEM.