32S G. E. COGHILL 



Figs. 51 to 54 Early swimming stage (No. 557, sections 2-1-1,5,7,11). X 200. 

 Four sections selected from a transverse series through the brain in the vicinity 

 of the entrance of the root of the trigeminal nerve. The massing of the 

 ganglia against the brain is shown here, a relation which should be noted in the 

 study of figures 1-4. Figure 51 is the most rostral in this set, and figure 54 the 

 most caudal. In figure 51 the ophthalmic ganglion (G.oph.) appears with a 

 crescentic piece of the Gasserian ganglion (G.G.) on its ventral surface. The 

 fibers from this ganglion enter in figure 52 (R.oph.)., while the root of the Gasserian 

 ganglion enters in figure 53 {R.G.G.) more dorsally. This section is 28 m caudad 

 of the last. In figure 54 the motor root of the nerve appears. 



