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Description of Cells. 

 Distribution. — The giant ganglion cells of Ctenolabrus form a 

 single median longitudinal row in the dorsal portion of the cord (Fig. 1). 

 They lie within the dorsal fissure, their upper surfaces being on a level 

 with the dorsal limit of the cord, and are covered by the membrana 

 prima (Fig. 3). Each cell is surrounded by a capsule formed of three 

 parts: 1) the membrana prima, which is arched above each cell (Figs. 3 

 and 5, mb. pr.); 2) the neuroglia fibres (fbr. n'gl), which come oft 

 from this membrana prima and extend downward to the canalis cen- 

 tralis, and 3) the fine neuroglia network (ret. n'gl). 



The capsules have an internal diameter of one and a half to two 

 times that of the cell, so that each cell is surrounded by a space, in 

 which it is partly supported by the numerous dendrites which run off 

 from the cell to the surrounding neuroglia. 



The giant cells extend from the posterior end of the fissura rhom- 

 boidalis caudad through the anterior end of the cord (Fig. 1). The 

 largest cells are near the anterior end of the series, and there is some 

 diminution in size posteriorly. The cells are as a rule more closely 

 set anteriorly, being separated from each other by intervals of from 

 one-fourth to one-half their diameter. The intervals between successive 

 cells increase posteriorly to three and four times the diameter of the 

 cells, the last few cells being irregularly placed at even greater inter- 

 vals (Figs. 1, 2). There is a tendency for the cells to become aggre- 

 gated into groups of three or 

 four cells each. In the an- 

 terior portion of the series 

 mutual crowding may influence 

 the form of the cells, or may 

 result in pushing some of the 

 cells either to one side of 

 the median line, or downward 

 (ventrad) below the level of 

 the others. Occasionally two 

 cells may be found in the 

 same transverse section lying 

 side by side. 



•mi.pT. 



Fig. 3. Transverse section of the anterior part of the cord of Ctenolabrus cceruleus. 

 The outline of the gray matter is shown by dotted lines, can. c. canalis centralis; cl. gn. 

 giant ganglion cell; cps. Capsula; fbr. lateral fibre bundel of the giant cells; fbr. n'gl. 

 neuroglia fibres ; mb. pr. membrana prima ; M. fbr. Mauthnee's fibres ; rx. d dorsal root, 

 rx. v. ventral root of spinal nerve. X *5. 



