388 OEIGINAL AETICLES. 



round, oval, fusiform, pyriform, cx'escentic, triangular, stellate, or 

 otherwise irregular, and have from at least two to eight processes 

 which extend in different directions — transversely, obliquely, and 

 longitudinally — forming part of the longitudinal bundles, the com- 

 missures, and roots of nerves. 



Nearly the whole inner half of the cervix cornu is occupied by 

 the remarkable and important column of cells, the posterior vesicular 

 column, (see M. fig. 3 and 4) extending throughout the whole length 

 of the cord, but varying somewhat in size and appearance in different 

 regions. Both in man and mammalia its diameter is greatest in 

 the upper third of the lumbar enlargement. The processes of these 

 cells are prolonged in every direction — transversely, longitudinally, 

 and obliquely : transversely they are continuous on the one hand with 

 the roots of the nerves, and on the other with the posterior com- 

 missure. The smallest cells doubtless belong to the connective tissue. 

 The anterior, or more opaque portion, of the posterior cornu, con- 

 tinuous with the cervix, presents a large proportion of longitudinal 

 fibres, to which indeed its opacity is owing. Its transverse fibres are 

 continuous Avith the roots of nerves, and with the longitudinal 

 columns. The cells are of small size, for the most part fusiform or 

 oval, having their long axes in the direction of the opaque or longi- 

 tudinal nerve roots. 



Schroeder van der Kolk, while he does not recognize the indepen- 

 dent existence of the posterior vesicular columns, nevertheless speaks 

 of several distinct columns of multipolar cells. In like manner Len- 

 hossek speaks of the cells in the posterior horn being accumulated 

 laterally, but asserts that the existence of Clarke's posterior vesicu- 

 lar column is not established. 



In the filum terminale a fringe only of grey substance is found 

 surrounding the dilated canal except in front, at the bottom of the 

 anterior fissure. This fringe contains a number of cells which re- 

 semble those of the connective tissue. As it ascends, the grey sub- 

 stance increases in quantity and projects forward to form the anterior 

 cornu, at the extremity of which a few large cells are grouped to- 

 gether. Through the lumbar region these large cells increase in 

 number, in projiortion to the size of the anterior roots of the nerves 

 and form several large groups, chiefly in the outer half of the cornu. 

 These cells are round, oval, fusiform, triangular, or stellate ; their 

 delicate processes are from two to eight or more in number, extend 

 in different directions and divide into numerous branches— some pro- 

 longed into the antero-lateral white columns, others into the anterior 

 roots of nerves. 



B. Nerve cells of the gelatinous substance (g. fig. 4). These are, 

 a. large, h. small, and c. intermediate ; the large cells are found 

 among the semi-circular fibres which run within the external border 

 of the gelatinous substance, and never extend beyond the middle of 

 its depth. They are more or less oval, fusiform, crescentic and ii-regu- 

 lar, containing distinct nuclei, and giving off ii'om two to six processes. 



