NERVUS TERMINALIS IX AMIA 



67 



This is the first indication of the ganglion of the nervus terminalis 

 which, however, cannot be made out with certainty in some 

 cases with specimens nine to twelve hours older. This indicates 

 a rather wide range of variability with regard to its time of ap- 

 pearance. The cells of the aggregation at this early date are not 

 greatly different from those elsewhere among the olfactory fibers. 

 In other words, all of the cells along the olfactory nerve are in- 



5* 



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Fig. 6. Horizontal section of Amia during the second day after hatching. 

 Shows the anterior end of the neural tube and part of the olfactory placode and 

 nerve. Note the nuclei at a in the olfactory nerve near its origin from the placode. 

 This is the point of origin of the cells of the nervus terminalis, not to be distin- 

 guished at this time from sheath cell nuclei. Iron hematoxylin and acid fuchsin. 

 X 340. 



different in character and still embryonic. Occasional mitoses 

 have been found along the nerve in this and earlier stages. 

 When the ganglion cells can be recognized they are slightly 

 larger than the indifferent cells and their nuclei are more vesicular 

 while their cytoplasm stains more deeply. Wherever the in- 

 different cells are taking on the characters of sheath cells, their 

 nuclei have become elongated and stain more deeply than their 



