ON DISTRIBUTION OF THE CELLS IN THE INTERMEDIO-LATERAL TRACT. 123 



This number is considerably less than the real number, because 24 sections were entirely 

 lost owing to the accident already referred to. In so far as the graph is continuous, 

 the upper end of the segment is similar to that of D. 10. The lower two-thirds show a 

 marked return to a spire-like arrangement and to an increase in the size of the groups, 

 the maxima being generally very high, reaching in section 312 to 55 on the right and 

 in section 302 to 45 on the left side. The groups are more sharply separated than in 

 D. 10, but they cannot be enumerated owing to the loss of sections. 



In this segment the reticular group assumes an increasing importance, although it 



C-L. ■ rn . 



u 



Fig 



17 (D. 10, 208, R.).— The rounded projection of the lateral 

 horn and its position at a level corresponding to the posterior 

 part of the column of Clarke are shown. The apical and 

 reticular groups form an almost continuous row of cells at 

 the margin of the grey matter. The inner boundary of the 

 group is very indefinite. There are also a few outlying cells. 



Ud 



Frc. 18 (D. 10, 225, L.).— As on the right side, the 

 rounded form of the lateral horn, and its recession 

 to a plane much behind that of the central canal, 

 are shown. The scattered cells and indefinite 

 boundary of both apical and reticular groups of cells 

 which are continuous are also seen. 



does not yet exceed the apical group in numbers. Near its lower end as many as 22 

 cells were counted in individual sections. The group possesses the same character and 

 relative position as in D. 10, but its limits are somewhat more easily determined. 

 There are no complete intervals between the apical groups. The apical cells are arranged 

 somewhat similarly to those in D. 10, with the occasional occurrence of a small separate 

 anterior group. The lateral horn is rounded as in D. 10 in the upper part (fig. 19, D. 

 181, L.), but at the lower end the spike reappears on the right side (fig. 20, D. 11, 

 312). 



Tivelfth Dorsal Segment. — This segment was divided into 405 sections. The inter- 

 medio-lateral tract contains 8545 cells on the right side and 7888 on the left. The 



