Negative Characters.—Absence of typical hemiplegic or monoplegic distribution of symptoms. Rarity of head symptoms, as headache, vertigo, mental disturbance; of lesions of the optic nerve. Absence of epileptiform convulsions. Absence of such grouping of motor and sensory symptoms as would exactly correspond to the area of distribution of one or more large nerve-trunks. The above symptomatic indications are, of course, of the most general meaning only, and are liable to exceptions and subject to varying conditions. The DIAGNOSIS of the exact localization of lesions in the spinal cord, considered from the clinical standpoint, is perhaps best arrived at by following an anatomical and physiological order of subdivision of the problem into three questions, as follows: FIRST QUESTION.—BEING GIVEN SYMPTOMS INDICATING DISEASE LIMITED TO ONE OR MORE SYSTEMS OF THE SPINAL CORD, TO DECIDE WHICH ARE AFFECTED. Physiology and the results of embryological and pathological researches justify us in making a general division of the spinal cord, for purposes of diagnosis, into two great systems, whose limits are fairly well known—viz. the æsthesodic or sensory system, and the kinesodic or motor system. The following outline diagram (Fig. 5) of section through the spinal cord exhibits the ascertained limits of the two systems. [Illustration: FIG. 5. Diagram of a Transverse Section of the Spinal Cord through the Cervical Enlargement: The æsthesodic system is shaded, the kinesodic system unshaded. Parts of the æsthesodic system: (1) Posterior nerve-roots; (2) posterior gray horns; (3) fasciculi cuneati (columns of Burdach, inclusive of posterior root-zones); (4) fasciculi graciles (columns of Goll or posterior median columns); (5) ascending cerebellar fasciculi; (6) columns of Clarke. Parts of the kinesodic system: (7) Anterior roots; (8) anterior columns (inclusive of anterior root-zones); (9) anterior gray horns; (10) crossed pyramidal fasciculi; (11) direct pyramidal fasciculi (columns of Türck); [10 and 11 are the intraspinal prolongation of the cerebral motor tract]; (12) lateral columns, of ill-defined limits and unknown functions; P. R., posterior roots; P. S., posterior septum; A. R., anterior roots; A. F., anterior fissure.]