VI 



SYMPATHETIC SYSTEM 



375 



Another argument adduced by Schultz against the view that 

 the sympathetic ganglia act as true reflex centres is that stimula- 

 tion of both post-ganglionic and pre-ganglionic fibres has the same 

 effect ; and that no summation can be seen from the latter, such as 

 is observed in the central nervous system. 



Intimately connected with the functional importance of the 

 sympathetic ganglia is the question whether, after separation from 

 the cerebrospinal axis, they are capable of sending tonic impulses 

 to the peripheral organs which they innervate. This point, too, 

 has received various answers. 



The simplest method of solving it evidently consists in 

 severing the pre-ganglionic fibres on one side of the body, and the 

 post-ganglionic on the other, or in extirpating the whole ganglion. 

 As the results can be compared on the two sides of the body it 

 should be easy to deduce the influence exercised by the ganglia 



FIG. 198. Mechanism of action in pseudo-, or pre-ganglionic axonal, and true reflexes. (Langley.) 

 A, true reflex ; J5, pseudo-reflex ; C, common diagram for A and B. 



alone, apart from the cerebrospinal axis. The cervical sympathetic, 

 and the superior cervical ganglion which has a dilatator action on 

 the pupil, are well adapted for this experiment, but the results 

 obtained by various authors (Budge, Braunstein, Langendorff, 

 Kowalewsky, Schultz) disagree. According to the three first, the 

 pupil is contracted for some hours to one or two days after the ex- 

 tirpation of the cervical ganglion, which implies that the ganglion 

 really has a tonic dilatator action, on suppression of which the 

 pupil contracts. But when the influence of the ganglion is 

 removed without irritation no difference is observed in the width 

 of the pupils. 



Similar researches have been made on the ciliary ganglion. 

 This ganglion normally exerts a tonic action on the sphincter 

 pupillae, which is maintained reflexly by the light that impinges 

 on the retina, and excites the ganglion by way of the optic 

 nerve and mesencephalon. Section of both optic nerves in an 

 animal causes dilatation of the pupil ; according to Schultz and 

 Lewandowsky the ciliary ganglion has no influence on this, for 



