(_a_) Single symptoms, such as atrophy or atrophic paralysis of some one muscle or muscular group innervated by the hypoglossal, facial, or spinal accessory nerves. For example, unilateral atrophy of the tongue, when not due to neural injury, is quite surely the representative of destruction of one hypoglossal nucleus. It is possible that some cases of peripheral facial paralysis, so-called, or Bell's palsy, and cases of paralysis of the sterno-mastoid and trapezius, are not due to neural lesion, but to primary disease of the nuclei of the facial and spinal accessory nerves, either as poliomyelitis or as progressive cell-degeneration and atrophy. A similar reserve must be used in speaking of the localization of small lesions in the oblongata, causing diabetes mellitus, polyuria, albuminuria, and salivation. From experiments upon animals and a few post-mortem examinations in human cases we know that such lesions may occur and cause the symptoms, but their recognition during the patient's life is at the present time next to impossible. (_b_) The symptoms may be complex and belong to the general class of crossed paralysis, the mouth, face, tongue, and larynx being paralyzed (often with anæsthesia of the face) on one side, while the extremities are paralyzed on the other side. Such a symptom-group would indicate a large lesion (tumor) in one lateral half of the oblongata, more especially in its ventral aspect. These localizations will be studied more in detail farther on, under the general head of Crossed Paralysis due to Lesions of the Base of the Brain. {81} IV. Localization of Lesions in the Encephalic Mass. Under this head, to prevent repetition and to facilitate condensation, we will consider the various localizations which can now be diagnosticated in the cerebrum, basis cerebri, and cerebellum. It would be of the greatest advantage to preface these statements by a full summary of the anatomical and physiological data on which the localizations rest, but space is wanting for such an exposition, and the reader who is not already familiar with these branches of medical science will have to seek information in other accessible works.[8] [Footnote 8: Ferrier, _The Functions of the Brain_, Am. ed., N. Y., 1876; Charcot, _Lectures on Localization in Disease of the Brain_, Am. ed., N. Y., 1878; Seguin, E. C., “Lectures on the Localization of Spinal and Cerebral Diseases,” _N. Y. Medical Record_, 1878; Ranney, _Applied Anatomy of the Nervous System_, N. Y., 1881; Meynert, _Psychiatry: A Clinical Treatise on Diseases of the Fore-brain_, Part I., Am. ed., 1885.] In a general way, encephalic lesions are distinguished by the following: