268 G. E. COGHILL 



appears in two parts, a dorsal, from the ganglion on the vagus, 

 and a ventral, from the ganglion on the ninth nerve. There are 

 no perceptible ascending and descending divisions of these root 

 fibers within the brain at this stage. 



2. The general cutaneous component. The jugular gangHon 

 holds about the same position relative to the other ganglia as in 

 the younger stage, although there is now no apparent connec- 

 tion with the skin in its more caudal portion. It does' connect 

 with the skin, however, at a point near the second post-auditory 

 lateral line primordium. This strand of cells is in very close 

 association with the ganglionic projection to this primordium. 

 It forms an incipient r. auricularis vagi. 



3. The visceral sensory component. The epibranchial placode 

 over the first branchial pouch is now massive and has a broad 

 connection with the visceral ganglion of the ninth nerve (fig. 2, 

 G.Vis.IX). It is now contributing cells, apparently, to the gan- 

 glion. The latter extends along the lateral line division of the 

 nerve to the brain. Its attachment to the brain is shown in 

 figures 30 and 31 {R.Vis.IX). 



A projection of the visceral ganglion of the vagus still con- 

 nects with a placode-like mass of cells situated over the second 

 branchial pouch. The larger portion of the ganglion projects 

 caudad and ventrad towards the other visceral pouches, near 

 which it ends in indefinite clusters of cells. A slender strand of 

 indifferent cells reaches from the ganglion to the brain, in which 

 there may be a few root fibers (fig. 32, R.X). In figure 32 the 

 strand of cells which represents the root (G.X), extends caudad 

 between the brain and the myotome (M). Here a single root 

 fiber appears. This may, however, be a motor fiber. No root 

 fibers can be positively recognized as arising from cells in the 

 ganglion. 



C. THE COILED-REACTION STAGE 



1 . The lateral line component. The lateral fine ganglion of the 

 ninth nerve still reaches to the skin, but a relatively large strand 

 of fibers without sheath cells now spreads across the primordium. 

 This is an incipient r. supratemporalis IX. The ganglion has 



