(_d_) Various combinations of the above lesions occur, and may be recognized positively during life: (1) Combined sclerosis of the posterior columns and of the crossed pyramidal fasciculi (3 and 10), indicated by ataxia with paralysis, absence of patellar reflex, tendency to contracture, pains, and anæsthesia less marked than in typical posterior spinal sclerosis. This symptom-group is usually found in children; it is pre-eminently a family disease, and is known as Friedreich's disease. Similar cases also occur in adults as a strictly personal disease. (2) Secondary degeneration of the pyramidal tract (10 and 11), with more or less localized atrophy of cells in the anterior horns (9) coexists in two forms: First, in a few cases of cerebral hemiplegia with contracture, and pathological atrophy of various muscles on the paralyzed side; second, as a distinctly spinal bilateral affection, characterized by a spastic or tetanoid state of the lower extremities, and a mixture of atrophic paralysis (vide (_a_)), with contracture in the arms and hands. This latter form is the amyotrophic lateral sclerosis of Charcot. SECOND QUESTION.—BEING GIVEN SYMPTOMS INDICATING A TOTAL TRANSVERSE LESION OF THE SPINAL CORD, ONE INVOLVING ITS VARIOUS SYSTEMS AT A CERTAIN LEVEL, TO DETERMINE THE ELEVATION OR FRONTO-CAUDAL SITUATION OF THE LESION. This question is usually easy of solution by the following method: Since a transverse lesion of the spinal cord gives rise to both motor and sensory symptoms of horizontal, paraplegic distribution caudad of the lesion, the first thing to do is to determine accurately the upper level of the symptom, either the line of anæsthesia or the limit of paralysis. The former is always much more definite than the latter, and usually serves as the guide to diagnosis, indicating accurately the uppermost part of the lesion. In the thorax the levels of sensory and motor symptoms nearly coincide, but in the extremities the operation of Van der Kolk's law of distribution of motor and sensory fibres of nerve-trunks must be borne in mind, although it does not apply as strictly in this case as in nerve lesions strictly speaking. Gowers's diagram will prove very serviceable in making a diagnosis of transverse lesions, and will also prove of use in the study of vertebral injury and disease, as it indicates with sufficient accuracy the relation between vertebræ (spinous processes) and segments of the spinal cord. (Vide Fig. 2.) The following are the principal transverse localizations of disease which are usually recognized during life by the above procedure: