NEW GROUP OF NERYE-CELLS 
IN' THE 
SPINAL CORD OF THE FROG 
(RANA PIPIENS AND EANA HALE GINA). 
JOHN J. MASON, M. D 
[.REPRINTED FROM THE NEW YORK MEDICAL JOURNAL, DECEMBER, 18T9.] 
In the posterior (inferior) portion of the brachial enlarge- 
ment, quite near the third and fourth pairs of spinal nerves, 
I find a distinct mass of ganglion cells, the nuclei of which 
measure in rana pipiens about :0125-:015 m.m., and are more 
nearly spherical than those of the larger cells of the (anterior) 
inferior horns, or than those of the smallest cells. This fact in 
regard to the form of the nuclei can be seen in fresh prepara- 
tions. Anteriorly in longitudinal sections, this mass or column 
extends, at least in this species (rana pipiens), as far as a plane 
about three millimeters behind the large brachial nerve roots. 
The group appears to be a numerous one, and in transverse sec- 
tions, where it is seen lying near the outer margin of the gray 
substance, just above the superior border of the central canal; 
often twelve and sometimes twenty nuclei can be counted. Ao 
similar group exists in the spinal cord of rana pipiens, if we 
except a small one of from three to five cells, seen in trans- 
verse sections of the middle portion of the conus medullaris. 
The location of this group observed both in longitudinal and 
transverse sections, and the medium size of the nuclei con- tained in the ganglionic bodies composing it, are two constant 
characteristics which I have established beyond doubt by the 
use of sufficient time and material. Karabanowitsch * divides 
the nerve-cells of the frog’s spinal cord into three classes: 
the largest, the medium-sized, and the smallest cells, basing 
his division upon measurements of nuclei. His “ sensitive 
cells,” or those of the second category, had nuclei measuring 
:015 m.m., and were therefore taken from the group above 
described, although the existence of the latter seems to have 
escaped his notice. He noticed (and his researches were made 
on comparatively fresh preparations) that the protoplasmic 
material or cell wall, so called, is less highly colored by car- 
mine than is that of the large inferior (anterior) horn cells, 
I am able to confirm this observation, but can not agree with 
him in regarding them as embryonic structures. Reissner f 
makes two classes only, large and small cells, and refers to 
none of medium size, nor did he notice or figure any such 
group as that which I have described. 
He noted fully the separation into two groups which oc- 
curs just below the second pair of nerves, but here the superior 
(posterior) group lies in cross-sections below the level of the 
central canal, and is composed of cells with large nuclei.; 
whereas that which furnishes the subject of this article lies 
above the superior margin of the canal, and consists of cells 
with medium-sized nuclei, as before stated. Wyman,£ on the 
“ Hervous System of Rana Pipiens,” found but one distinct 
group : those of the inferior (anterior) horns, which are re- 
peatedly called posterior horns, although the accompanying 
cut makes his meaning plain. 
Have we here to do with the hornologue of Clarke’s col- 
umns ? Gerlach, on the nerve cells of the human spinal cord, 
in Strieker’s “ Hand-Book ” (translation) states, on page 635 ; 
“ The largest cells are found in the anterior, the smallest in 
* “TJeber den Ban des Rtickenmarkes vom Frosche.” St. Petersburg, 
1872. 
t “Der Ban des centralen Nervensystemes der ungeschwanzten Batra- 
chier.” Dorpat, 1864. 
f Published by Smithsonian Institution, Washington, 1853, vid. pp. 
19, 20. the posterior horns, and those of medium diameter in that 
region of the spinal cord lying to the side and a little hack of 
the central canal—the columns of Clarke.” The group, then, 
which we are here considering corresponds, in all points ex- 
cept the extent of space which it occupies antero-posteriorly, 
with the cells of the lateral columns. The reader is referred 
to the u Anatomical Hand-Book ” of Henle for a careful re- 
sume of the work of Clarke and Stilling, and for much origi- 
nal text, with plates on the lateral tracts of the spinal cord, 
hearing in mind that, as before stated, in the posterior (lower) 
portion of the lumbar region, a trace of this group is also 
found in the frog.