2l8 NERVE COMPONENTS OF BONY FISHES. 



Between the fourth and the third spinal ganglia no 

 ganglion cells appear in the sympathetic trunk, which, 

 however, rises up and again becomes embedded in the 

 third spinal ganglion, where it develops a ganglion of its 

 own, as in the previous case. Some of the sympathetic 

 fibres pass through the ganglion without losing their 

 medullary sheaths. This sympathetic ganglion sends 

 fibres from its cephalic end into the ventral ramus and 

 others, as before, back into the spinal ganglion. 



The sympathetic trunk now resumes its former position 

 between the m. retractor arcus branch ii dorsalis and the 

 head kidney nearly up to the level of the second spinal 

 ganglion. Here a sympathetic ganglion is found, which 

 fuses with the caudal end of the spinal ganglion and the 

 sympathetic trunk runs embedded in the latter to its 

 cephalic tip, where there is another sympathetic ganglion, 

 which effects the usual relations with the ventral ramus 

 (r. V. 2). The trunk then again passes down to its 

 former position. 



Opposite the second vertebra there is another ganglionic 

 enlargement which extends forward as far as the r. ven- 

 tralis of the first spinal nerve (r. v. i). The nerve trunk, 

 however, turns ventrad just cephalad of the m. retractor 

 arcus branchii dorsalis and enters a large ganglion {sy. 7), 

 within which it divides, one part continuing cephalad, the 

 other passing ventrad and mesad to a small ganglion 

 coeliacum {g. ca-/.) lying ventrally and laterally of the 

 centrum of the second vertebra. From this ganglion a 

 strong sympathetic commissural nerve runs under the 

 vertebra to a similar ganglion of the opposite (right) side, 

 which in turn is in like manner related to a ganglion of 

 the chain of that side and from which the n. splanchnicus 

 is given off. The latter nerve is confined to the right 



