1. Cilio-spinal center, situated in the cord between the lower cervical and third dorsal vertebra. It is connected with the dilatation of the pupil through fibers which emerge in this region and enter the cervical sympathetic. Stimulation of the cord in this locality causes dilatation of the pupil on the same side; destruction of the cord is followed by contraction of the pupil.

2. Genito-spinal center, situated in the lower part of the cord. This is a complex center and comprises a series of subordinate centers for the control of the muscular movements involved in the acts of defecation, micturition, ejaculation of semen, the movements of the uterus during parturition,

etc.

3. Vasomotor centers, giving origin to both vaso-constrictor and vasodilator fibers, which are distributed throughout the cord. Though acting reflexly they are under the dominating influence of the center in the medulla.

4. Sweat centers are also present in various parts of the cord. Paralysis from Injuries of the Spinal Cord.

Seat of Lesion.—If it be in the lower part of the sacral canal, there is paralysis of the compressor urethræ, accelerator urinæ, and sphincter ani muscles; no paralysis of the muscles of the leg.

At the Upper Limit of the Sacral Region.—Paralysis of the muscles of the bladder, rectum, and anus; loss of sensation and motion in the muscles of the legs, except those supplied by the anterior crural and obturator, viz. : psoas iliacus, Sartorius, pectineus, adductor longus, magnus and brevis, obturator, vastus externus and internus, etc.

At the Upper Limit of the Lumbar Region.-Sensation and motion paralyzed in both legs; loss of power over the rectum and bladder; paralysis of the muscular walls of the abdomen interfering with expiratory move

ments.

At the Lower Portion of the Cervical Region.—Paralysis of the legs, etc., as above; in addition, paralysis of all the intercostal muscles and consequent interference with respiratory movements; paralysis of muscles of the upper extremities, except those of the shoulders.

Above the Middle of the Cervical Region.-In addition to the preceding, difficulty of deglutition and vocalization, contraction of the pupils, paralysis of the diaphragm, scalene muscles, intercostals, and many of the accessory respiratory muscles; death resulting immediately from arrest of respiratory

movements.

MEDULLA OBLONGATA.

The Medulla Oblongata is the expanded portion of the upper part of the spinal cord. It is pyramidal in form and measures one and a half inches in length, three-quarters of an inch in breadth, half an inch in thickness, and is divided into two lateral halves by the anterior and posterior median fissures, which are continuous with those of the cord. Each

VIEW OF CEREBELLUM IN SECTION, AND OF FOURTH VENTRICLE, WITH THE
NEIGHBORING PARTS. (From Sappey.)

1. Median groove fourth ventricle, ending below in the calamus scriptorius, with the longitudinal eminences formed by the fasciculi teretes, one on each side. 2. The same groove, at the place where the white streaks of the auditory nerve emerge from it to cross the floor of the ventricle. 3. Inferior peduncle of the cerebellum, formed by the restiform body. 4. Posterior pyramid : above this is the calamus scriptorius. 5. Superior peduncle of cerebellum, or processus e cerebello ad testes. 6, 6. Fillet to the side of the crura cerebri. 7, 7. Lateral grooves of the crura cerebri. 8. Corpora quadrigemina.-After Hirschfeld and Leveille.

half is again subdivided by minor grooves, into four columns, viz.: anterior pyramid, lateral tract and olivary body, restiform body and posterior pyramid.

1. The anterior pyramid is composed partly of fibers continuous with those of the anterior column of the spinal cord; but mainly of fibers derived from the lateral tract of the opposite side, by decussation. The