NERVUS TERMINALIS IN REPTILE AND MAMMAL 105 



ganglion cells appear in the dorsal division, which the writer 

 attributes to the nervus terminalis (fig. 12 D, E). As the olfactory 

 ner\'e approaches the nasal sac, its ventral division spreads out 

 to innervate the medial diverticulum as well as the dorso-lateral 

 wall (fig. 10, 12 D). The dorsal division breaks up into several 

 strands which pass downward over the medial surface of this 

 diverticulum to run beneath the nasal sac and reach its extreme 

 lateral portion as above described. Meantime several small 

 strands leave the dorsal division and bend rostrad over a partly 

 separate rostral portion of the medial diverticulum, to which 

 they are distributed. These small strands bear clumps of gan- 

 glion cells (fig. 12 E) which mark them as strands of the nervus 

 terminalis. 



Taking both the 10 and 20 mm. embryos into account, it may 

 be said that the ganglion terminale in Emys is scattered in clumps 

 of variable size along the nerve from its root to the terminal 

 branches near the nasal sac. 



The foregoing description shows that in the embryos of certain 

 reptiles and mammals the nervus terminalis enters the brain at 

 a point somewhat removed from the median plane but otherwise 

 holding the same relation to the primordium hippocampi, pre- 

 commissural body and neuroporic recess which the root holds in 

 selachians. Its fibers arise from bipolar ganglion cells which are 

 collected into a compact ganglion terminale (pig) or are gathered 

 into several clumps in the course of the nerve and its branches 

 (turtle). In the pig the nervus terminalis is clearly distributed 

 to the vomero-nasal organ and in the turtle to a medial diver- 

 ticulum of the nasal sac which presumably corresponds to the 

 vomero-nasal organ or a part of it. In man the fibers mingle 

 with the olfactory strands of the nasal septum. 



Two authors have dealt with the nervus terminalis in mam- 

 mals, de Vries ('05) and Dollken ('09). De Vries' paper is not 

 accessible to me, but from the references to it by other authors 

 it appears that he recognized a vomero-nasal nerve and vomero- 

 nasal ganglion whose root entered the medial surface of the 

 rhinencephalon caudal to the bulbus olfactorius. He saw also 

 ganglion cells scattered in the course of the nerve. He inter- 



