597 
1907-8.] Middle Cells of Grey Matter of Spinal Cord. 
cells, resembling, both in size and appearance, the motor cells of the anterior 
cornua. They are usually single, but, rarely, two may occur together. 
Argutinski’s observations (4) must now be referred to. His description 
of the middle cells of the new-born child is fuller than that of Waldeyer, 
but differs from his in several points. In particular, he finds a regular and 
sharply defined segmentation of the middle cell column, but limits the 
system to the dorsal portion of the cord. After a careful and thorough 
examination of the spinal cord both in longitudinal and in transverse 
sections — including serial sections of a complete cord — I am convinced 
that this segmentation of the middle cells does not exist, and, further, that 
what Argutinski has described is the reticular group of the intermedio- 
lateral tract. His description is too long to quote in its entirety ; briefly, 
it is that of a double chain of segmented cell columns (Seitenhornzellen 
and Mittelzellen), limited to the dorsal portion of the cord, the segmentation 
of the two columns being parallel, but sharper in the middle cell group. His 
description is based principally on the examination of longitudinal sections, 
although, as he himself states, conclusions as to position can only be drawn 
from transverse sections. That this double chain exists I fully admit, but 
I hold that it is formed of the two constituent groups of the intermedio- 
lateral tract, and not of the middle cells and lateral horn cells. Waldeyer, 
as pointed out by Bruce, includes the reticular group of cells in his 
Seitenhornzellen. Argutinski does not do so ; he only includes the apical 
group of the intermedio-lateral tract under that heading. If, throughout 
his paper, we read for “ Seitenhornzellen,” apical cells or apical group, and 
for “ Mittelzellen,” reticular cells or reticular group, we get an excellent 
description of the complete intermedio-lateral tract. The points of agree- 
ment between his “ Mittelzellen ” and the reticular group of cells as described 
by Bruce (whose observations I entirely corroborate, except in some small 
points, probably due solely to the difference in age of the subjects from 
whom the cords were obtained) are as follows : — 
(1) Longitudinally limited almost to the dorsal portion of the cord. 
(2) Lie very near to the lateral horn cells (apical group), sometimes 
even in direct contact with them. 
(3) Lie posterior and internal to the lateral horn cells, usually close to 
the re-entrant reticular angle. 
(4) Direction of cells — chiefly inwards and forwards. 
(5) Shape of cells — like the lateral horn cells (apical group), but broader. 
(6) Parallel segmentation of the apical and reticular groups (Seitenhorn- 
and Mittelzellen of Argutinski), the segmentation being a much 
sharper one in the latter of the two groups. 
