[ 437 J 
XXII. Further Besearches on the Grey Substance of the Synnal Cord. 
By J. Lockhaet Clahke, Esq., F.B.8. 
Eeceived June 17, — Eead June 17, 1858. 
Since the appearance of my second series of investigations on the structure of the 
Spinal Cord, certain modifications in the method I employ have enabled me to carry my 
inquiries to a still greater extent, and in many respects beyond the limits of what was 
actually known on this important subject. By this modified method the elementary 
ner\ e-tissues undergo less alteration from their natural state j for the most minute nerve- 
cells and their processes, as well as the finest fibres, are permanently preserved, and 
display a sharpness of outhne unattainable by any other mode of preparation employed 
at the present day ; while sections the one-twelfth of an inch in thickness may be 
rendered perfectly transparent^. 
Many of the older anatomists, from Baetholinus downwards, had observed that the 
grey substance of the spinal cord is softer, more delicate and more vascular than the 
surrounding white columns ; but Eolando was the first to point out a diversity in its 
structure. He observed, chiefly in quadimpeds, that on each side the posterior third of 
the grey crescent consists of a peculiar cineritious substance, which presents a different 
aspect from that which forms its two anterior thirds : it is different in colour, darker, 
and less redf. Eolando, however, assigned too large a space to this “new substance,” 
which does not comprise so much as the posterior third of the grey crescent, but forms 
only a comparatively naiTow and curved lamina or band around the extremity of each 
cornu, and, when viewed in a thin section by transmitted light, is found to be actually 
much paler and more transparent than the rest of the grey crescent. That this lamina 
is the part indicated by Eolando appears evident on examining his plates J. 
Now I propose, also, to make a primary but different division of each posterior cornu 
* See Appendix. 
t “Non h molto difficile il vedere nelmidoUo spinale di bue, di maiale e di pecora, che le coma posteriori 
della sostanza cinericcia, che in questi si mostrano molto pih spesse e piugrosse che neU’ uomo, sono formate 
in ^an parte da una sostanza cinericcia particolare, che presenta un aspetto diverso da quello, che si osserva 
ne a porzione che forma i due terzi anteriori della mezza luna. Questa nuova sostanza e piu gelatinosa, 
CIO c e^fa si che prende eziandio un colore diverse, e che in generale e meno rossigno, e di un colore pin 
oscuro. ’ meercle AnatomicTie sulla Struttura del Midollo Spinale (con figure), 1824, Torino, p. 60. He 
ates that it was only in quadrupeds that he succeeded in distinctly seeing this new substance, partly 
ecause m them the spinal cord may be obtained in that state of freshness which is more favourable for 
servation, and partly because this substance is found there in greater abundance ; but that, nevertheless 
in Man, unequivocal traces of it may be seen in the lumbar region. 
+ Some authors, however, seem to think that the gelatinous substance comprises a larger poiiion of each 
MDCCCLIX. Q 
