228 Mary IsaheUe Steele 



ages were so small and so curved that it was almost impossible to 

 obtain satisfactory longitudinal sections. 



A few points of interest, however, have been observed. These 

 for the most part serve to corroborate the observations of Herbst 

 rather than to add to them. An examination of the appendages 

 in toto show that the old optic nerve either extended as a nerve 

 trunk through the greater part of the length of the regenerated 

 appendage or that other structures were developed in the new 

 appendage which appeared to be continuous with the old optic 

 stump (Figs. 30, 34, 38). Sections confirm the observations made 

 from surface examinations. A large number of intermediate 

 stages would be necessary, however, to determine whether the 

 regeneration of the nerve trunk had been from the optic nerve 

 stump outward or whether peripheral regeneration had developed 

 nerve fibers inward which unite with the optic nerve stump. The 

 fact, however, that the nerve trunk appears more distinctly differ- 

 entiated in the proximal part of the appendage than in the distal 

 may probably be regarded as an indication that the regeneration 

 proceeds from the proximal end outward. 



Sections of these appendages show that the interior is chiefly 

 occupied by nerve cells and fibers. The nerve fibers appear to be 

 continuous with the nerve fibers of the old optic nerve stump. 

 The nerve cells are grouped into ganglion-like masses which are 

 scattered pretty generally through the length of the appendage. 

 The brain sheath is continuous with the loose fibrous sheath which 

 envelops the mass of nerve cells and fibers. 



Fig. 1'] shows a somewhat diagrammatic section through the 

 brain and the proximal end of a heteromorphic appendage that 

 developed within sixty-seven days after the operation. It was 

 necessary to combine two sections in order to show the continuity 

 of the optic nerve with the nerve trunk of the appendage. There 

 can be no doubt, however, that they form a continuous structure. 

 One feature is noticeable both in sections and in whole prepara- 

 tions. That is, that the optic trunk leading to the regenerated 

 appendage is much smaller in diameter than the one opposite. 

 This fact suggests that probably only a part of the fibers of the 

 optic nerve have persisted (Figs. 34, 38). 



