114 J. B. JOHNSTON 



Fig. 3 Pig, 15 mm. Model of part of the right hemisphere and nasal sac, 

 seen from the medial surface. The model includes the optic stalk, whose slit- 

 shaped cavity is seen, and the medial wall and frontal pole of the hemisphere. 

 The groove in the hemisphere is the fissura prima of His. The root of the nervus 

 terminalis is directed backward in the paraterminal region. The olfactory 

 nerve forms a dark background for the ganglion terminale in the drawing. It 

 is at this point that olfactory fibers coming from the vomero-nasal organ sepa- 

 rate from the nervus terminalis fibers and enter the olfactory bulb in the olfac- 

 tory nerve roots. The two kinds of fibers run together in the bundles which 

 go to the vomero-nasal organ. 



Fig. 4 Human embryo of 31 mm. (Huber collection XLVii). ]\Iodel of rostral 

 portion of right hemisphere showing the relations of the nervus terminalis. The 

 ganglion terminale is distinct from the root of the olfactory nerve but distally 

 the nervus terminalis fibers mingle with olfactory' nerve fibers. 



