614 Proceedings of the Royal Society of Edinburgh. [Sess. 
REFERENCES. 
(1) Waldeyer, “Das Gorilla-Riickenmark,” Abliand. d. honig. Ahad. d. Wiss. 
zu Berlin, 1888. 
(2) Bruce, “Distribution of the Cells in the Intermedio-lateral Tract of the 
Spinal Cord,” Trans. Roy. Soc. Edin ., vol. xlv., pt. i., No. 5, 1906. 
(3) Onuf and Collins, The Sympathetic Nervous System , 1900. 
(4) Argutinski, “ On a regular segmentation in the grey matter of the spinal 
cord in the new-born and on the Middle Cells,” Arch. f. micros . Anat ., xlviii., 1897, 
p. 496. 
DESCRIPTIONS OF FIGURES. 
[ Photographs untouched save outlining of the grey matter . ] 
Plate I. 
Fig. 11. C 3—200 L ( x 33 ). 
The middle cells are scattered in the base of the anterior horn and in the 
areas of the lateral horn and reticular formation, those in the anterior horn 
being of larger size. They form a fairly compact group in the central area, and 
there is also a group of smaller-sized cells in Clarke’s column area. 
Fig. 12. C 6— 274 L ( x 32 ). 
- The middle cells occur in the manner most characteristic of the cervical 
enlargement, viz. as a broad band of cells stretching from the reticular angle 
towards the central canal. There are also some scattered cells anterior to this, 
and a very few small cells in the area of Clarke’s column and base of posterior 
horn. 
Plate II. 
Fig. 13. D 4—23 R ( x 40 ). 
Shows apical group of intermedio-lateral tract occupying most of the lateral 
horn, and with some outlying cells in the white matter. The reticular group 
cells are larger in size, tend to be elongated along a line running inwards and 
forwards from the reticular angle, and the group lies some way internal to the 
edge of the grey matter. There are a very few scattered cells in the base of the 
anterior horn ; some centrally, near the tip of the reticular group, and a small 
group of smaller, more rounded, post-central middle cells. 
Fig. 14. L 3—259 L ( x 32 ). 
The middle cells form a large central aggregation. There are small groups 
post-centrally and behind the anterior median motor group. 
A few cells in the reticular area and base of posterior horn. 
{Issued separately September 2 , 1908 .) 
