56 CHARLES BROOKOVER 



This latter statement of Allis is based on findings in sections of a 

 single young specimen of Amia. He found this posterior bundle 

 in gross dissections of the adult, but says he never could find how- 

 it ended in the brain. His illustrations (plate xxxvii) of the adult 

 brain shows the posterior root of the nerve running well back 

 between the optic chiasm and the brain. As I understand the 

 terms "lobus" and "lobus olfactorius" employed by Allis in the 

 above quotations from him, he uses them to indicate what neurol- 

 ogists now call the olfactory bulbs in w T hich are located the mitral 

 cells and their glomeruli. Olfactory lobes are now commonly 

 used to indicate olfactory centers in the forebrain proper. Con- 

 sequently, it would appear that Allis traced some of the fibers of 

 the nervus terminalis in young Amia into the anterior end of the 

 olfactory bulbs and others into the posterior ventral portions of 

 the olfactory bulbs. He found the main bundle in the adult in 

 the same position as in the young, but traced some of its fibers 

 farther caudad without determining their ending. Locy ('03) 

 examined the nerve in adult Amia and says it does not have the 

 conspicuous separateness which characterizes it in selachians. 



After examining a large number of adult Amia brains macro- 

 scopically I could never be absolutely certain that I saw any- 

 thing different from olfactory fibers, which often break up into 

 various small bundles before joining the olfactory bulbs. Any- 

 thing that seemed to resemble the alleged posterior connection 

 near the optic nerve, could never be distinguished with certainty, 

 when cleared in xylol, from connective tissue or blood vessels. 

 Kappers ('07) had no better results from the study of Weigert 

 and Bielschowsky preparations of the brains of adult Amia 

 which, however, had been removed from the cranial cavities 

 before they came into his hands. 



By examining the young stages of Amia in which Allis described 

 the large cells that distinguished the nervus terminalis from the 

 remaining olfactory bundles, it was easy forme to confirm his find- 

 ings in the main. This led me to undertake a detailed examination 

 of the early embryology of the nervus terminalis. As it had been 

 described as a separate nerve by Locy ('05) in selachians, it 

 occurred to me that it might be connected in Amia and Lepidos- 



