l8o "Journal of Comparative Neurology and Psychology. 



fixed, the changed relations of the adult being due to a farther 

 growth of the olfactory bulbs rostrad rather than to a recession of 

 the nervus terminalis caudad. In the adult the olfactory capsules 

 lie far rostrad of the olfactory bulbs, while in the larva they lie 

 in about the same transverse plane, the olfactory nerves passing out 

 to them almost laterally. 



In none of my preparations have I been able to trace the fibers 

 of the nervus terminalis distally more than about 1 mm. beyond the 

 olfactory bulbs. I have not examined the peripheral relations of the 

 olfactory nerve and nasal capsules in the adult frog. In several 

 preparations of frog tadpoles (probably R. pipiens) I have found 

 cells scattered along the peripheral course of the nervus olfactorius 

 which differ from the sheath cells of the fila olfactoria. The clear- 

 est case observed is a large tadpole taken just before the metamor- 

 phosis, which was prepared by the method of Cajal and cut into 

 horizontal sections. Scattered along the ventral surface of the olfac- 

 tory nerve in the middle part of its course are more than 100 nuclei 

 which differ conspicuously from the sheath nuclei among which 

 they lie, being round or broadly oval and twice as wide as the nar- 

 rowly oblong sheath nuclei. They are scattered along the olfactory 

 nerve from its foramen through the skull to the point where it 

 lu'eaks up to spread over the olfactory mucous membrane. From 

 the similarity of these nuclei to those found by Brookover on the 

 nervus terminalis of ganoids and teleosts I incline to regard them 

 as belonging to ganglion cells of the nervus terminalis of the frog, 

 though I have not been able to demonstrate their fibrous connec- 

 tions. 



The exact central connection of the nervus terminalis also demands 

 further investigation. The single impregnation of the terminal 

 arborizations in the lamina terminalis of the voune; lan^a is not 

 altogether conclusive and this observation must be verified and 

 extended before much weight can be given to it. One is, however, 

 struck by the similarity between this observation and the descrip- 

 tions of Locy of the central relations of the nervus terminalis in 

 the selachians. 



In conclusion, it seems clear that the nerve here described in 



