THE TRACT OF GOWERS

Abstract

1. In the term “Gowers' bundle” or “tract” all the ascending ventro‐lateral fibres should be included and not the spino‐cerebellar fibres only.2. If a lesion in the lower thoracic region injures only ventro‐lateral fibres, it is found on tracing the resulting degeneration upwards that there is a gradual transference of spino‐cerebellar fibres from the region of Gowers' bundle to that of Flechsig's, these transferred fibres being distributed to the cerebellum by way of the restiform body along with the other fibres of Flechsig's tract.3. The ventral spino‐cerebellar fibres arise from the lower cells of Clarke's column of the same side. These cells become chromatolysed as the result of ventro‐lateral lesions which involve the bundle of Gowers only. On the other hand, if the dorsal cerebellar tract of the cord alone is injured, or the inferior cerebellar peduncle divided, most of the cells at the lower extremity of Clarke's column do not undergo chromatolysis.4. The dorsal and ventral spino‐cerebellar fibres must no longer be regarded as two distinct and separate systems. They form parts of one and the same system, and connect the cells of Clarke's column of the same side with the cerebellum. This system divides at the level of the medulla oblongata, the greater number of fibres passing to the vermis cerebelli by the inferior cerebellar peduncle, a smaller number passing to the vermis by the superior cerebellar peduncle.5. The ventral cerebellar fibres lie mostly at the periphery of Gowers' bundle, and are not appreciably different in size from the dorsal cerebellar fibres. The fibres lying more centrally are, for the most part, smaller and finer. These do not pass to the cerebellum but to successive segments of the cord, to the lateral nucleus of the medulla oblongata, to the pons, to the anterior and posterior colliculus of both sides, to the substantia nigra of the same side, and to the thalamus of the same side.6. The spino‐vestibular tract, and the dorsal and ventral collateral plexuses, which have been considered to arise from the dorsal cerebellar tract, may take origin also from the transferred fibres of the tract of Gowers.7. Section of the spino‐cerebellar tracts in the spinal cord of the monkey produces no permanent physiological effect.