Sargent, Giant Ganglion Cells of Ctcnolabriis. 



187 



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 

 rhomboidalis caudad through the anterior end of the cord, (fig. 

 i). The largest cells are toward the anterior end of the series, 

 and there is some diminution in size posteriorly. They are as 

 a rule more closely set anteriorly, being separated from each 

 other by intervkls of from one-fourth to one-half their diameter. 

 The intervals between the adjacent cells increases posteriorly to 

 three and four times the diameter of the cells, the last few 

 being irregularly placed at perhaps greater intervals (figs, i and 

 2). The cells tend to become aggregated in groups of three or 

 four, separated from other groups by wider intervals. In the 

 anterior portion of the series mutual crowding may influence 

 the form of the cells, or may result in pushing some of the 

 cells to one side of the median line, or downward below the 

 level of the others. Occasionally two cells may be found in a 

 transverse section lying side by side. 



On either side of that 

 portion of the canalis cen 

 trails where it widens out 

 and opens into the fissura 

 rhomboidialis there are sim- 

 ilar cells bilaterally placed, 

 usually two on each side 

 but the number may vary 

 from one to three (fig. 2, 

 a). In fig. I, these are 

 shown projected upon the 

 median plane {a). Rarely 

 similar giant cells are found 

 which do not lie in the 

 dorsal fissure but lie lat- 

 erally, deeply buried in the cord, (fig. i, b). This condition 

 occurs in about one case out of 300. 



Size. — In the youngest fishes 3 cm, in length the cells 

 have an average diameter of 7 or 8 « . In the various stages 



Fig. J. Diagrammattic transverse sec- 

 tion of the anterior part of the cord. The 

 outlines of the grey matter are shown in 

 dotted lines, r.ci. radix dorsalis; c.c. can- 

 alis centralis ; mf. Mauthner's fibers. 



