SYMPATHETIC GANGLIA 237 



sympathetic nerves associated with them in Menidia. The obser- 

 vations of these two investigators, on two distinct types of fishes, 

 do not differ materially and indicate that the cranial sympathetic 

 ganglia in fishes are more or less intimately related to the roots of 

 the X, IX, VII, V, and III cranial nerves. 



The following observations on the development of the. cranial 

 portion of the sympathetic nervous system in fishes are based on 

 preparations of embryos of the common toad fish (Opsanus tau). 

 The topographical relationships of the cranial sympathetic gan- 

 glia and the sympathetic nerves associated with them, as far as 

 the latter may be traced in preparations of embryos, conform 

 more or less closely in this species to Herrick's description of 

 the topographical relationships of the cranial sympathetic gan- 

 glia and nerves in adult Menidia. The topographical relation- 

 ships of the cranial portion of the sympathetic trunk and the cra- 

 nial sympathetic ganglia to the first spinal and the X, IX, VII, V, 

 and III cranial nerves in an advanced embryo of Opsanus are 

 illustrated semidiagrammatically in figure 1. This figure indi- 

 cates a less intimate relationship between the sympathetic trunk 

 and the IX cranial nerve than Herrick found to exist in Menidia. 



Ganglia on cranial 'portion of sympathetic trunk 



The cranial portion of the sympathetic nervous system arises, 

 in embryos of Opsanus, quite as early as do the sympathetic 

 ganglia and nerves in the trunk region. In embryos 5 to 6 mm. in 

 length, the sympathetic trunk may be traced cephalad as far as 

 the ganglionic complex of the trigeminal nerve. The primordia 

 of the several sympathetic ganglia along the course of the cranial 

 portion of the sympathetic trunk are already present. 



In conformity with the plan adopted by other authors, we shall 

 refer to the sympathetic ganglia in the course of the cranial por- 

 tion of the sympathetic trunk by number, beginning with the one 

 most anterior, which is intimately associated with the Gasserian 

 ganglion, and numbering caudad from 1 to 6. In tracing the 

 development of these ganglia it will be found most convenient 

 to begin with the one most posterior in the series and consider 

 the successive ganglia in order. 



