XXXIl] THE SPINAL BULB 251 



The funiculus cuneatus (Burdach's column), with a small 

 triangular or rounded mass of grey substance projecting into it 

 the beginning of its nucleus. 



The caput of the posterior horn, a round deeply stained 

 mass near the surface ; this is now the nucleus of the bulbar 

 or descending root of the 5th nerve ; between the substantia 

 gelatinosa and the surface are many small nerve fibres bulbar 

 or descending root of the 5th nerve but they are not very 

 obvious in this region in carmine preparations ; amongst them 

 are a few bundles of large fibres. 



Ventro-laterally of the caput and on the surface a patch of 

 large fibres the dorsal cerebellar tract. 



In the median ventral region extending nearly up to the 

 central canal, the bundles of fibres of the pyramidal decussa- 

 tion ; in the lateral region these bundles are separated by grey 

 substance forming the reticular area ; ventrally of this is seen 

 the anterior cornu cut off by decussating fibres from the grey 

 substance round the central canal. 



Dog. The decussation of the pyramids is much more regular, the 

 fibres crossing in smaller bundles, so that the double crossing is more 

 obvious; the fun. gr. is thin, and its nucleus is fairly developed; the 

 anterior cornu is less cut off from the caput and the reticular area is 

 more marked ; the layer of fibres covering the caput is distinct. 



2. Section through the upper part of the pyramidal 

 decussation.. Note : 



The central canal is now on the dorsal side of the middle of 

 the section. 



The nucleus of the funiculus gracilis spreads throughout all 

 the central parts of the funiculus. 



The nucleus of the funiculus cuneatus is larger than in 1 

 and forms a rounded stained mass ; the funiculus is broader and 

 less deep. 



The lower part of the bulbar root of the 5th and its nucleus 

 is on a level with the central canal. 



The central grey substance is a round mass ; its lateral 

 boundary being formed by a number of small bundles of fibres 

 the beginning of the sensory decussation. 



