XXXl] SPINAL CORD 241 



Note also the increase in grey substance dorsally of the central 

 canal ; the caput of the posterior cornu forming a roundish mass 

 near the surface of the cord ; a thin cap of small fibres on the 

 caput (descending fibres from Gasserian ganglion), the superficial 

 group of large fibres ventrally of the caput (the direct cerebellar 

 tract). 



DEMONSTRATIONS. 



1. Section of cord of dog or cat (Marchi's method, 

 cp. Notes) above a region of transverse section. Note 

 the black globules of medulla showing degeneration : 

 in Goll's column; in the posterior and external part 

 of the lateral column (direct cerebellar tract); and 

 (more diffusely) in the antero-lateral columns, chiefly 

 near the surface (ascending antero-lateral tract). 



2. Section similar to 1, but below the point of 

 injury. Note 



The m degeneration in the centre of the posterior 

 part of the lateral column (the crossed pyramidal 

 tract). 



The diffuse degeneration in the antero-lateral 

 columns, chiefly at the surface of the anterior column 

 (descending antero-lateral tract). 



A few degenerated fibres may also be present in the posterior 

 columns (descending root fibres and endogenous fibres). 



3. Three sections of cord of dog or cat (Marchi's 

 method) above, below and through a segment of which 

 the posterior roots of one side are in a state of degene- 

 ration. Note in the segment, the degeneration of the 



L. 16 



