THE NERVOUS TISSUES. 



155 



garded as dendrites, the others as neuraxes. As to the significance 

 to be attached to the single process, the theory of v. Lenhossek 



Fig. 115. Ganglion cell from the Gasserian ganglion of a rabbit ; stained in methylene- 



blue (intra vitam). 



(94, I) that it represents an elongated portion of the cell, and that 

 therefore the origin of the dendrite and that of the neuraxis are in 

 this case close together, is very plausible. In the embryo these 

 ganglion cells are at first bipolar, a process arising from each end, 

 of a spindle-shaped cell ; as de- 

 velopment proceeds, the two pro- 

 cesses approach each other and 

 ultimately arise from a drawn-out 

 portion of the cell - body, the 

 single process. (Fig. 116.) 



The sympathetic ganglia are 

 composed mainly of the cell- 

 bodies and dendrites (also some 

 structures to be mentioned later) 

 of neurones of the sympathetic 

 nervous system. In nearly all 

 vertebrates, and with but few ex- 

 ceptions in any one ganglion, 

 these neurones are multipolar and 



Fig. 116 Three ganglion cells from 

 a spinal ganglion of a rabbit embryo. The 

 cells are still bipolar. Their processes 

 come together in later stages, and finally 

 form the T-shaped structure seen in the 

 adult animal ; chrome - silver method ; 



resemble morphologically the 



multipolar ganglion cells of the anterior horn of the spinal cord, 



though they are somewhat smaller. In the cell-body there may be ob- 



