

ON DISTRIBUTION OF THE CELLS IN THE INTERMEDIO-LATERAL TRACT. Ill 



Psychiat., vol. ii. p. 582) to regard the reticular series of cells as distinct from the 

 apical one, and consequently endeavoured to enumerate them independently of each 

 other. This was, in those sections where the two sets of cells were not in contact, a 

 simple matter ; but in a great many sections it was quite impossible to trace any line 

 of demarcation between the two, so closely were they fused. On making a second 

 enumeration so as to include the reticular cells along with those at the apex of the 

 lateral horn, the remarkable fact became evident that the effect on the groups plotted 

 out in the chart was simply this, that the maxima were increased and the minima 

 remained unaltered. A. further careful examination of the relation of the two rows 

 of cells throughout the dorsal region and the first lumbar segment showed that in 

 following them through a series of sections it was always possible to trace them into 

 intimate connection with each other. The posterior or reticular cells were therefore 

 included in and enumerated as an integral part of the intermedio-lateral tract. This 

 opinion was not arrived at without full consideration, and it was satisfactory to find 

 on a subsequent study of Waldeyer's work on the spinal cord of the gorilla that it had 

 the support of his authority. 



The results of the examination of each segment may now be stated. 



Eighth Cervical Segment. — This was divided into 280 sections. Its intermedio- 

 lateral tract contains 429 cells on the right and 595 on the left side. These are 

 distributed as follows (see graph) : The upper fourth part of the segment is practically 

 devoid of cells, there being only one cell on the right side (situated in section 68), and 

 on the left side one each in sections 67 and 69. 



The second fourth contains three small groups of cells, separated by wide intervals. 

 The number of cells seen in any one section never exceeds four, and the number in 

 the largest group (E. 108-119) is thirty-one. 



The third fourth contains on the right side three small groups. If the cells on the 

 left side of sections 144-1 62 inclusive be regarded as belonging to one group, and those 

 from section 173 to 187 as comprising another, there are two small groups and the 

 beginning of a third on the left side. 



The lowest fourth contains by far the largest number of cells in the segment. In 

 the right side these are distributed in four and on the left in three groups. The 

 largest of these is on the left side. It extends from section 192 to 227, and contains 

 286 cells. The preponderance of the cells on the left over those on the right is due 

 mainly to this nucleus. 



Throughout the whole segment the cells of the intermedio-lateral tract are situated 

 in the white matter. They are all " outlying," as Sherrington has termed them, 

 although they vary somewhat in their distance from the grey matter. They are 

 connected with this, however, by strands of connective tissue. Their long axes corre- 

 spond to the direction of these strands, and for the most part run parallel to the adjacent 

 border of the grey matter, being thus oblique outwards from behind forwards. 



No reticular group is seen. Such cells as are situated behind Clarke's column and 



