606 
Proceedings of the Royal Society of Edinburgh. [Sess. 
also be similar, and difficult to separate from the innermost cells of the 
reticular group, but many are smaller and more rounded. They may form 
a band round Clarke’s column, and may lie directly behind it. The middle 
cell distribution is everywhere casual and erratic. 
D12. — See fig. 7. — Very similar to Dll. With the great increase of Clarke’s 
column, the post-central cells are crowded characteristically into band form. 
L 1. — See fig. 8. — Increase in size and number along with the other cell- 
a. Abundant anterior middle cells, large and small. 
b. Apical group, intermedio-lateral tract. 
c. A few cells representing the reticular group of the intermedio-lateral 
tract. 
d. Large group of post-central middle cells. 
e. Small para-central group. 
/. Clarke’s column. 
There are only a few scattered middle cells in the central area. 
systems. Anterior cells particularly numerous, either as groups in various 
parts of the base of the anterior horn, or very commonly scattered thickly 
over it. Central cells also common, of typical middle cell character as regards 
their occurrence. Both anterior and central cells are polygonal, very like the 
intermedio-lateral tract cells individually, and not always readily separable 
from that tract when lying near its boundaries. Post-centrally, they are 
also mostly of the same type, but both here and occasionally in the reticular 
formation there are some of the smaller, more rounded cells. 
L 2.— A large increase in the number of middle cells, pari passu with 
that of the grey matter. Many of the individual cells are also larger. 
The cells may be in groups or scattered irregularly over the basal and 
