356 MR. J. LOCKHART CLARKE ON CERTAIN FUNCTIONS OF THE SPINAL CHORD. 
beautiful order and design so conspicuously manifested by organic life in the form- 
ation of every part which science has revealed to the inquiring eye. Every fibre, 
probably, has its own fixed and appointed course, in accordance with the particular 
function it is destined to perform. 
Explanation of the Plates. 
PLATE XXIII. 
Represents a longitudinal section through the cervical enlargement of the spinal 
chord of the Cat, from the 8th to the 12th pair of nerves. Magnified 30 diameters=*^. 
P, C. Posterior white columns. A, C. Anterior white columns. G. Grey sub- 
stance between the white columns. P. Posterior roots of the nerves, consisting of 
three kinds,— a, b and c. The second kind, b, traverse the posterior columns at first 
obliquely towards the mesial line, that is, in a plane oblique to that of the section, 
and were therefore divided near the surface of the chord. A. Anterior roots of 
the nerves. A, C. A portion of the anterior column, showing the arrangement of 
their longitudinal fibres. 
PLATE XXIV. 
Represents a longitudinal section through the lumbar enlargement of the spinal 
chord of the Ox. Magnified 30 diameters. 
P, C. Posterior columns, showing the intricate interlacement formed by the pos- 
terior roots of the nerves. P. Posterior roots. A, C. Anterior white columns. 
A. Anterior roots of the nerves. G. The anterior and posterior grey substance 
traversed by the fibres of the anterior and posterior roots of the nerves, g. The 
substantia gelatinosa. 
In both Plates the vesicles have been omitted in order to avoid obscuring the fibres, 
which were observed by means of Ross’s half-inch object-glass, with No. 2 eye-piece, 
giving a power of 150 diameters. 
* The outlines of the drawings were made by means of a power of 40 diameters, but were reduced nearlj 
one-third by the engraver. 
