242 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



geminal nerve, these three centres give origin to the fibres 

 of the three distinctively branchial nerves — the seventh, 

 ninth, and tenth. Each of these nerves, apart from the 

 somatic sensory fibres from the spinal fifth tract, belongs 

 essentially to the visceral or sympathetic system. The 

 fibres from the spinal fifth tract are given off from the 

 root of the nerve immediately outside the skull (but 

 sometimes intracranially) and pass to the skin of the back, 

 where, as before stated, they function as somatic sensory 

 nerves. The remainder of the fibres from the other two 

 tracts form the trunk of the branchial nerve, and just over 

 the visceral cleft are placed two ganglia (which, as a rule, 

 apparently form a single mass), one ganglion for each set 

 of fibres. Arrived at the cleft, the branchial nerve, 

 according to the old view, was supposed to divide into 

 three bundles — one supplying the lining of the pharynx, 

 one passing along the posterior edge of the arch in front 

 of the cleft, and the third skirting the anterior edge of the 

 arch behind the cleft. This distribution of a branchial 

 nerve has been made use of to prove that there were 

 primitively no gill clefts between the mouth and the first 

 branchial cleft, since the facial nerve forks over the spir- 

 acular cleft, gives off a palatine branch corresponding in 

 every respect with the visceral branch of a posterior 

 branchial nerve — the remaining two bundles entering into 

 pre- and post- branchial relations with the mandibular 

 and hyoid arches respectively, thus showing the impro- 

 bability of any arch ever having existed between these 

 two. With regard to the division of the branchial nerve 

 into three bundles, the facts are as follows : — The trunk 

 consists, as has been previously described, of two bundles — 

 a visceral motor bundle from the motor nucleus, and a 

 visceral sensory bundle from the fasciculus communis 

 system. Theiatter passes downwards and divides to form 



