Fig. 93.— Schema of the neurones forming the sympathetic nervous system (Huber: Journal of Com- 

 paraif . L897, vol. vii.i. 



A solid black line designates the axone from an efferent neurone, with its cell-body in the ventral horn 

 of the cord, and the terminal brush ending in a striated muscle (m.n.). 



A black line crossed by short dashes designates the axone from an afferent neurone, the cell-body of 

 which is in the spinal ganglion, and the peripheral axone of which terminates in the epidermis or some 

 special sense-organ (g.n.). 



An interrupted black Km indicates an axone of similar origin to the one just described, but distributed 

 with the fibres of the sympathetic system (s.s/.). At the periphery it terminates in a free ending 

 (s.s.f.H)) or in a Pacinian corpuscle (s.s/.(2)). 



A blue line shows a preganglionic fibre (of Langley), the cell-body of the neurone being located in the 

 lateral horn of the cord. The axone leaves the cord by the ventral root (as a fibre of very small calibre), 

 passes in the white ramus | W.R.), and terminates by a pericellular basket about the body of a sympa- 

 thetic neurone (drawn in red). 



The various places where such an axone may terminate are indicated as follows: o. axone passing 

 through the chain-ganglion (I.C.6.) to terminate within the next higher chain-ganglion ; b, axone passing 

 as does (a), but terminating in the next lower chain-ganglion {II.C.O.) ; c, two axones ending in a gan- 

 glion of this same segment (I. CO.); d, axone passing through the chain-ganglion of the segment and 

 ending in a prevertebral ganglion (Pr.v.G.) : e, axone passing through both a chain-ganglion and a pre- 

 vertebral ganglion to end in a peripheral ganglion I Periph.6.) ; /, axone which gives off a collateral branch 

 to one ganglion {J.CO.) and passes on to terminate in a more distal ganglion (Pr.v.G.). Fibres arranged 

 like (/) probably account for some of the reflexes obtained from sympathetic ganglia ; g and h. axones 

 representing fibres which regularly pass to any given ganglion from the ganglia above and below it. 

 The sympathetic neurones are drawn in red, and about their cell-bodies terminal baskets of other axones 

 (always in blue) are shown. They enter the mixed nerve by the gray ramus (G.R.). m, the axones of the 

 sympathetic neurones, terminate: i, in the muscular coats of the blood-vessels (vaso-motor endings); 

 j, in the muscular coals of the viscera (viscero-motor endings), and in heart-muscle (not specially shown 

 in the figure) ; k, in glands (secretory fibres); I, in other sympathetic ganglia (a doubtful form of termi- 

 nation). 



The figure further shows two " afferent " sympathetic neurones (Dogiel), in dotted red ; o, arising in a 

 peripheral ganglion [Periph.0.) and terminating in the prevertebral ganglion [Pr.v.O.) : p, arising in the 

 chain ganglion (I.C.G.) and passing to the spinal ganglion, to terminate about Dogiel's spinal ganglion- 

 cell of " type two," q (represented in solid back); g, spinal ganglion-cell (Dogiel's " type-two "), the ter- 

 minals of W Inch form baskets about the bodies of the ordinary spinal ganglion-cells. 



