no THE SPINAL CORD AND CEREBELLUM 



The fact that the cerebellar tract does not undergo 

 degeneration when the posterior nerve-roots alone 

 have been severed, but only when the cord itself is 

 injured,* shows the connection between it and the 

 spinal nerves to be an indirect one. 



The remainder of the white matter of the cord — that 

 is to say, the greater part of the anterior division and 

 a considerable part of the lateral division — has been 

 differently defined by various writers. 



The fibres of the antero-lateral ascending tract are 

 supposed to take their origin in the middle zone of 

 the gray matter, and often degenerate in company 

 with those of the cerebellar tract, t Those of the 

 antero-lateral descending tract, apparently described 

 by Bechterew and Marchi as the anterior-marginal 

 bundle, occupy a position parallel and close to those 

 just mentioned, and are said to be connected with the 

 cerebellum and to constitute a path for centrifugal 

 impulses.! Internal to the antero-lateral ascending 

 and descending tracts and the crossed pyramidal 

 tracts, between these and the gray matter are the 

 anterior and lateral fundamental tracts ;§ whilst 

 immediately between the crossed pyramidal tract 

 and the posterior horn of gray matter is situated 

 a tract called by Bechterew the median bundle of the 

 lateral column. According to the same author there 

 is also a tract of fibres in the centre of the crossed 

 pyramidal tract which undergo descending degenera- 



* Foster, loc. cit, p. 963. + Bechterew, loc. dt., p. 89. 

 I Ibid., p. 81. § Ibid., p. 84. 



