442 ME. J. L. CLAEKE ON THE OEET SHBSTANCE OE THE SPINAL COED. 
identical character, may be traced through the white columm between the fibres, as far 
as the surface of the cord. The nuclei are more or less round or oral, and contain a 
number of delicate gi-anules. In a free state (see fig. 48 a and fig. 46 c) they aboimd m 
every part of both the grey and white substance, but sometimes they are partia y or 
wholly surrounded by a kind of shaggy, flocculent, or finely filamentous mass (fig. . 
below the letter e), while in other instances they ai-e attached to the suirotmdmg parts 
only by a few fine fibres. Now there is reason to beheve that this flocculent or a- 
mentous substance is really the remains of the cell in process of development into the 
surrounding tissue and sheath of the nerve-fibre ; for on exammmg the cord of an adiilt 
animal, I found that the nucleated cells had disappeared, while in the midst of the fila- 
mentous tissue between the nerve-fibres, the same kind oi nuclei were still present*. 
These observations, then, render it apparently impossible to pomt out the exact 
distinction between the connective and the true neiwe-tissue, and nnght suggest the 
question, whether there is any actual and essential difference between them, or whet er 
the connective tissue of the cord be intermediate in its nature, passmg on the one hand 
into tissue, and on the other into pia matei. 
2. The anterior or inner and more ofoke portion of the caput cornu is contmuous 
with the grey substance of the cervix, and surrounded behind and on each side by t e 
arched lamina of the substantia gelatinosa, with which it varies in shape at diftereiu 
regions of the cord (figs. 5 to 17, Plates XXI. XXV. & XXIII.). In some parts of 
the cervical and in the dorsal region, as seen in a transverse section, it projects into the 
gelatinous substance in the form of a cone, while in other regions its posterior bordei 
is more or less angular or rounded. Its elementary structuie, ui addition to blood- 
vessels and connective tissue, consists of— 
a. Longitudinal fibres. 
b. Transverse and oblique fibres. 
c. Cells. 
a The longitudinal fibres are collected into bmidles, and are the principal cause of 
the opacity of this portion of the caput cornu. They are broader and coai'ser than the 
fibres of the gelatimm mUtmce, which, however, they immediately adjoin. Sometimes, 
as in the neck, they form round the extremity of the cone a kind of arched band or roof, 
of the same shape and about the same depth as the snhstantia gelatimsa, which rests 
. I find that precisely similar nuclei are abundantly scattered throughout both the white and ^y sub- 
stance of the ceLmm and cerebellum. In tbe convolutions of the cerebellum, the nuclei, win h m a 
dense layer form the internal portion of the grey substance, and into which the fibres of t e w ii e su s a 
L penetrate, are for the most part a little difterent from those in the immediate neighborhood. They 
are generM, round or globular, are more uniform in she, and mostly contain a distinct and dear c^ . 
or globular nucleolus (as in fig. 46, Plate XXII., below the letter «). surrounded by fine ^nus 
like these, but frequently of larger size and sometimes containing tivo globulai nncleo i, ai y 
in the ffelatinous substance (see the two above fig. 46), but are not peculiar to this substance, 
also found in aU parts of the grey substance of the cerebrum. 
