236 PRACTICAL HISTOLOGY [XXXI 



out by the eye by a difference of tint, when no proper 

 septum is present. (Goll's column begins about the 

 lower third of the thoracic region, and increases in 

 passing upwards.) 



In the lumbar region there is an oval area of small nerve 

 fibres about the centre of the combined posterior columns, the 

 posterior septum running through its long axis. 



In the sacral region there is a triangular area of small fibres 

 in the combined posterior columns, the base of the triangle being 

 on this surface, and the posterior septum dividing it into two 

 equal halves. 



These areas must not be confused with Goll's columns. 



b. Differences in the grey substance. 



Relative amount of grey substance. The grey 

 substance is much larger in amount in the cervical and 

 lumbar swellings than in the thoracic region. 



Shape of anterior cornu. In the cervical and 

 lumbar swellings the anterior cornu has a large lateral 

 projection, in the thoracic region it forms a narrow 

 band with nearly parallel sides. The median border 

 is approximately parallel with the anterior fissure in 

 the cervical and thoracic regions, but curves away from 

 it in the lumbar region. 



The lateral cornu. In the thoracic region there 

 is a small lateral projection of the grey substance, the 

 lateral cornu, about midway between the anterior and 

 posterior cornu. (It is less distinct in the lower 

 thoracic region and varies in different sections.) 



Shape of posterior cornu. The neck of the 

 posterior cornu is narrow in the thoracic region, and 

 the apex is some distance from the surface of the cord 



