STUDY OF THE SPINAL CORD 
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in the cross bar of the H. The dorsal column of gray substance 
forms the dorsal region of the upright stroke of the H, the region 
opposite the cross bar is the lateral column, and the rounded 
region ventral to the cross bar is the ventral column. The latter, 
unlike the more pointed dorsal column, fails to reach the surface 
of the cord. 
The three funiculi of white substance upon each side, the 
dorsal one located between the median dorsal sulcus and the dorsal 
column of gray substance, the lateral one located between the 
lateral surface of the cord and the lateral boundary of the gray 
area, and the ventral one located between the ventral column of 
gray substance and the median ventral fissure. 
Compare sections through as many levels of the cord as are 
afforded by the material, and note the varying shapes, and the 
different proportionate amounts of the gray and white substance 
at different levels. Draw a section through two or more of the levels 
thus studied and show the general topography in each , noting in 
all cases the indefiniteness of the line separating the gray from the 
white substance. 
2. Microscopic Study. —Examine, mainly under low power, 
several sections of the spinal cord (Lab. SI. Coll.), and having 
established in each case the direction of the section with relation 
to the long axis of the cord, identify the following structures: 
The Meninges (dura mater, arachnoid, and pia mater).— 
Determine how many of these are present in each section, and the 
relation of each to the surface of the cord, the small root bundles 
(fila radicularia), and the ganglia, if these are present. 
The Epithelial Layer (ependyma) lining the canalis 
centralis, and any structures such as Reissner’s fiber, lying in 
the lumen. 
The Perikarya of Neurons in the Gray Nerve Substance.— 
In which column are these especially large and conspicuous? 
Where are they small and few? Are they at all grouped and where 
are such groups found? Look for sections which show the nucleus 
dorsalis (Clark’s column) in the dorso-medial region adjacent to 
the cross bar of the H. 
Fibers Extending from the Gray to the White Substance or 
vice versa .—Look especially for those which go to make up the 
