136 Journal of Comparative Neurology. 



rons in a metameric segment. In the construction of this dia- 

 gram I have been greatly aided by Fig. 840 of Vol. II, Part 



II, of Kolliker's Gewebelehre and also several figures in Vol. 



III, Part II, of Quain's Anatomy. 



In the figure 5. C. represents one half of the spinal cord ; 

 A. R., the anterior root; P. R., the posterior root with the 

 spinal ganglion ; P. S. B. , the posterior branch of the spinal 

 nerve ; L. S. B. , the lateral or mesial branch of the spinal 

 nerve; W. R., the white ramus; G. R., the grey ramus; /- 

 //-I/I C. G. , three sympathetic ganglia of the chain united by 

 intervening nerves ; Pr. V. G., a pre-vertebral ganglion; Periph. 

 G., a peripheral ganglion. 



In Fig. 13, the following colors have been used to desig- 

 nate neurons of different orders, and in the following way : — A 

 black line {in. n.) designates a motor neuron of the spinal cord, 

 with the cell body in the anterior horn, the end-brush in striated 

 muscle. A black line crossed by short black dashes [s. «,), a 

 sensory spinal neuron of a somatic nerve, ending in the epi- 

 dermis or in some special sense organ. The cell body of such 

 a neuron is in the posterior root ganglion. A71 interrupted 

 black line denotes a sensory, spinal nerve, accompanying effer- 

 ent sympathetic fibers to the viscera {s. s. /.). Such fibers, it 

 is assumed, come from cells in the posterior root ganglion, pass 

 to the sympathetic ganglia through the white rami, and through 

 the several sympathetic ganglia until they reach the periphery/ 

 there to end either in a free ending (s. s. f. (/) ), or in a Pacin- 

 ian corpuscle {s. s. f. {2) ). The neurons colored blue, are the 

 pre-ganglionic fibers of Langlcy or the 'central fibers'. I have 

 followed Fig. 240, of Quain's Anatomy, Vol. Ill, Pt. II, in 

 placing the cell bodies of such neurons in the lateral portion of 

 the anterior horn of the spinal cord. The neuraxes of such 

 cells leave the spinal cord through the anterior horn, and reach 

 the sympathetic ganglia through the white rami {W. R.), where 

 they terminate in peri-cellular baskets, enclosing the cell bodies 

 of the sympathetic neurons (red in the figure). 



The preganglionic fibers leaving the anterior root and the 



