1890.] Nerve-cells in the Mammalian Spinal Cord. 145 



formation numerous nerve-cells are to be found among the interlacing* 

 bands of nerve-fibres. These are often fusiform, but in many cases 

 multipolar ; they are for the most part small, but occasional large 

 individuals can be found ; the latter would appear always to be multi- 

 polar. Where the lateral column comes into contact with the lateral 

 limb of the substantia gelatinosa of the caput cornu posterioris 

 ganglion- cells can frequently be seen in it. The larger axis of these 

 cells is parallel to the outline of the caput cornu. They seem to exist 

 most numerously in regions, such as the lumbo -sacral, in which 

 medullated fibres, probably posterior root-fibres, sweep through the 

 deeper part of the lateral column round the lateral limb of the 

 gelatinosa as if to reach the base of the posterior horn. 



In the posterior columns outlying nerve-cells are also to be found, 

 especially in the human cord. In these columns the cells appear to 

 be outstanding members of the posterior vesicular group of Clarke. 

 They are best seen in the upper lumbar and lower dorsal regions. 

 They are large, measuring in some instances 70 fi across. In 

 appearance they closely resemble the cells of Clarke's column. They 

 are nearly always of broadly ovate shape. They appear always to lie 

 on or in close relation to those horizontal bundles of nerve-fibres 

 which curve in a ventro-lateral direction from the depth of the extero- 

 posterior column into the grey matter in the neighbourhood of the 

 posterior vesicular group. The longer axis of the cell is placed 

 parallel to the nerve-fibres it lies upon or among. Where a process 

 from the bipolar cell-body can be followed, it disappears in a direction 

 which is that of the surrounding nerve-fibres. The cell would seem 

 in the majority of cases to lie with its length in a plane at right 

 angles to the long axis of the cord. Frequently the cells lie close to 

 the grey substance of Clarke's column, but in some specimens they 

 occupy positions far removed from the grey matter ; they may even 

 lie near the periphery of the extero- posterior column. 



The chief interest attaching to nerve-cells lying in the white matter 

 of the spinal cord is that they may be supposed to be connected with 

 , the nerve-fibres among which they are, and that from that fact some 

 knowledge may be gained as to the anatomy of themselves, and of 

 the group of which they may be outlying individuals, or of the fibre- 

 bundles containing them. 



With regard to the cells existing among fibres passing to the 

 white commissure of the cord, it is legitimate to consider their 

 presence as evidence in favour of the view that some of the cells of 

 the median portion of the ventral grey horn are directly connected 

 with medullated fibres passing to or from the opposite half of the 

 cord by way of the anterior commissure. 



The cells in the lateral column outside the lateral horn may be 

 taken to point to the connection of the intermedio-lateral group of 



