90 The Neuroglia of the Spinal Cord of the Elephant 
nuclei appear in the marginal portion resulting from the division of 
those lying nearer the central canal. In the adult, after the application 
of the ordinary hematoxylin methods, for example, the marginal veil 
(cortex) of the spinal cord appears as a thin, lightly-stained homoge- 
neous, granular zone void of medullated nerve fibers and containing 
a few small spherical nuclei scattered in it and certain fine colorless 
fibrille which are perhaps neuroglia fibers. In the literature I have 
been unable to find any detailed descriptions of the adult marginal veil 
after treatment by any of the differential neurogha stains. In the ele- 
phant after this treatment, it appears as a dense feltwork of neuroglia 
fibers coursing in all directions and but slightly intermingled with white 
fibrous connective tissue from the adjacent pia mater. It contains no 
nerve fibers and is thicker on the dorsal and lateral aspects of the spinal 
cord than on the ventral. At best it is a relatively thin mantle, on 
measurement seldom showing a thickness of over 80 yw. In proportion 
to the abundance of neuroglia fibers, it contains remarkably few nuclei 
(see Fig. 1) and very seldom are any of these of the large vesicular 
variety. In this respect, when compared with other localities of the 
transverse section, it conforms to Aguerre’s observation that the number 
of neuroglia nuclei in a field is in inverse ratio to the abundance of 
neurogha fibers. In their abundance, length and arrangement, the 
fibers have all appearances of having been formed from a common 
syncytium rather than from or with reference to any arrangement of 
individual neuroglia cells. 
The entering radix posterior contains no fibers whatever which take 
the neuroglia stain until its nerve fibers penetrate the marginal veil. 
This fact is well differentiated by the Benda stain. The radix posterior, 
as it enters the cord, even apparently depresses the marginal veil on 
coming in contact with it. Once it breaks through this mantle, how- 
ever, its nerve fibers become richly intermingled with the blue staining 
neuroglia fibers. The nerve fibers of the radix anterior on the other 
hand, as they emerge through the marginal veil are accompanied a short 
distance beyond the confines of the spinal cord, by a few blue-staining 
fibers. My preparations, not being made with this point in mind, un- 
fortunately do not allow satisfactory observations as to how far these 
neuroglia fibers accompany the fila of the radix anterior nor how abun- 
dant they are. The radix anterior of the elephant arises by innumer- 
able small fila radicularia, most of which in the preparations were torn 
off close up to the surface of the cord. The fila of the radix posterior 
are considerably larger and in several sections quite an extent of a filum 
of this root remained attached to the cord. 
