OIL XLIL] REGIONAL DIFFERENCES IN CORD 621 



stance. This thin layer is wanting in the neighbourhood of the posterior nerve-roots. 

 The grey commissure is extremely thick. 



At the level of the fifth sacral nerve the grey matter is also in excess, and the 

 central canal is enlarged, appearing T-shaped in section ; whilst in the upper portion 

 of the filum terminate the grey matter is uniform in shape without any central 

 canal. 



