The group of fibres forming the dorsal spino-cerebellar tract takes origin as is well known from a considerable longitudinal extent of the spinal cord.
Owing to the regular accession of fresh fibres to it as it passes headward, its cross-area increases to culminate in the cervical region. The tract is believed to consist of fibres from cells of Clarke’s column (Flechsig’, myelinisation evidence, 1876; Mott2, degeneration evidence, 1890; Van Gehuchten3, Schafer3, Warrington3, chromato- lysis evidence, 1898, 1899).
Clarke’s column extends as an obvious cell- group from IIrd lumbar to IInd thoracic segments inclusive (dog). In the cervical region the tract will therefore consist of fibres derived from the lumbar and the whole thoracic region.
Are the fibres from the several levels of origin completely commingled in the cross-area of the tract, or do they, like the long fibres ascending the dorsal column, retain within the tract some regular subgrouping? Are for instance the lumbar fibres collected in the dorsal angle, the anterior thoracic in the ventral fraction, or vice versa?