MEDIATE SPINAL SYSTEMS. 807 



rise are not with certainty identified ; some may be contained in Clarke's 

 column, 1 but some lie at levels more caudal than the most caudal part of 

 Clarke's column, 2 and therefore more caudal than the main mass of the dorso- 

 lateral spino-cerebellar system. The fibres pass into the superior vermis 3 of 

 the cerebellum. The system is often called the ventro-lateral or conjunctival 

 spino-cerebellar, because its fibres wind back into the cerebellum by the 

 brachium conjunctivum. 



(ii.) Other spino-encephalic systems. — Some spinal cells thrust branches up, 

 it is said, into the mesencephalon, forming a spino-quadrigeminal 4 system. 

 The fibres of this system lie among the fibres of the ventro-lateral column in 

 the region of the ventral root-zone. Many of them decussate to run forward 

 through the bulb close to the ventro-lateral spino-cerebellar system ; they reach 

 the fillet. Instead of winding backwards and upwards to the cerebellum, they 

 pass into the roof of the mesencephalon, and end more in the anterior than in the 

 posterior corpus quadrigeminum. Others, it is said, proceed farther still, and 

 enter the diencephalon, ending in the ventro-lateral nucleus of the optic 

 thalamus, forming a spino-thalamic system. 5 Throughout the dorsal longi- 

 tudinal bundle of the cranial floor fibres exist, probably derived from the 

 cells of the ventral grey horn of the contra-lateral side of the spinal cord, 

 though probably only from the headmost region of the cord. Some ascending 

 spinal fibres seem to end in the grey matter of the ventro-lateral region of the 

 bulb. The ventro-lateral spinal column seems therefore to contain branches 

 from intraspinal cells that reach each of the main divisions of the brain except 

 the telencephalon, unless it be the n. lenticularis (Rossolymo). 



(b) Bncephalo-spinal. — Nerve cells of the formatio reticularis of the 

 bulb and of the pons possess, there is reason to think, branches that pass back 

 into the spinal cord. These are some of them direct and some crossed. The 

 former run partly in the longitudinal bundle and partly in the reticular forma- 

 tion to the cord, forming a system which extends into the cord, the fibres in 

 their spinal course lying in the ventral column to the median side of the motor 

 root-zone. The crossed part of the system passes the median raphe near its 

 origin, and descends in the lateral field of the reticular formation. Its spinal 

 portion consists of fibres in the dorsal part of the lateral column where the 

 fibres of the crossed pyramidal tract lie ; this system seems to extend through 

 the whole length of the cord. 



A system of fibres is found in the ventro-lateral parts of the cord, which 

 are stated to be derived from a group of bulbar cells (Deiter's nucleus) that forms 



of the tract (" Diagnosis of Diseases of the Spinal Cord"), and it is often called the tract 

 of Gowers. Singer examined it by experimental degenerations (Sitzungsb. cl. k. Alcad. d. 

 JVissensch. , Wien, 1881, Bd. Ixxxiv. Abth. 3). He considered it a spino-cerebellar tract, 

 so also Sehultze. Lowenthal {Bull. Soc. vomdoise d. sc. not., Lausanne, 1885, tome xxi. 

 p. 92, and "Diss.," Geneve, 1885) was the. first to prove its termination upward in the 

 cerebellum, a result confirmed by Auerbach, Virchoiu's Arcltiv, 1890, Bd. cxxi. ; Mott, 

 Phil. Trans., London, 1891 ; Tooth, Brain, London, 1892, vol. xv.; Schafer, "Quain's 

 Anat. ," 1893, vol. iii. p. 1, and others. 



1 Schafer, " Proc. Physiol. Soc," March 1899. 



2 E.g., Gowers' case in " Diag. of Diseases of Spinal Coi'd." See also Tooth, op. cil., and 

 St. Earth. Hosp. Rep., London, 1886, vol. xxi. 



s Lowenthal, op. eit. ; Auerbach, op. cit. ; Mott, op. cit. 



4 Mott, Brain, London, 1895, vol. xviii. ; v. Solder, Neurol. Centralbl., Leipzig, 1897 ; 

 Thomas, Gompt. rend. Soc. de biol., Paris, 1897, tome iii.; Rossolimo, Neurol. Centralbl., 

 Leipzig, Bd. xvii. 



5 Mott., op. cit. ; H. Patrick, Arch. f. Psychiat., Berlin, 1893, Bd. xxv. S. 31 ; Journ. 

 Nerv. and Merit. Bis., Fel). 1896 ; Fr. v. Solder, op. cit.; Alex. Bruce, Brain, London, 

 1896, vol. xix. ; Edinger, "Vorlesungen u. d. Bau. d. nerv. Centralorg.," Leipzig, 1889 ; A. 

 Tschermak, Arch. f. Physiol., Leipzig, 1898 ; Kohnstannn, Neurol. Centralbl., Leipzig, 

 1899, Bd. xviii. S. 14. 



6 Held, Abhandl. d. k. Cesellsch. d. Wissensch., Leipzig, 1892, Bd. xviii. S. 6 ; 

 Fusari, Riv. spcr. di freniat., Reggio-Emilia, 1896, tomo xxii. p. 417; A. Tschermak, 

 Arch. f. Physiol., Leipzig, 1898, S. 291 ; Ramon y Cajal, "Apuntos para el estudio, etc.," 

 Madrid, 1895. 



