102 J. B. JOHNSTON 



ganglion cells connected with its fibers have been stained also. 

 Further, a single preparation shows fibers which leave the periph- 

 eral strands of this nerve just distal to its ganglion, to join the 

 root of the olfactory nerve and enter the olfactory bulb. This 

 shows that the peripheral strands which have been described as 

 nervus terminalis contain also the fibers which persist in the adult 

 as the vomero-nasal nerve. 



THE SHEEP 



In embryos of the sheep of about 15 and 20 mm. the nervus 

 terminalis is clearly present. Its ganglion is somewhat less 

 sharply defined but in general it presents the same relations as 

 in pig embryos. 



HUMAN EMBRYOS 



In an embryo in the writer's collection (H. 16) of 15.3 mm. 

 ganglion cells appear medial to the root of the olfactory nerve 

 in a position corresponding to that of the nervus terminalis in 

 the pig. There are groups of ganglion cells found also in the 

 ventral and lateral parts of the olfactory nerve. They ares dis- 

 tinguished from neurilemma cells by their larger size, globular 

 nuclei and deeper stain. The bundles of the nervus terminalis 

 can not be traced in this embryo but the position of these gan- 

 glion cells suggests that the nervus terminalis may be distributed 

 in part to the lateral wall of the nasal sac. 



In an embryo of 9.5 mm. the ganglion terminate can not be 

 distinguished as it can be in pig embryos of the same length. 

 This embryo was received very fresh and its fixation is excellent. 



The embryo xlvii of the Huber collection, 31 mm. in length, 

 is cut in faultless sagittal sections 15m in thickness and stained 

 in hematoxyhn and congo red. A model has been made of a 

 sufficient portion of the right half of the brain adjacent to the 

 median plane to show the relations of the nervus terminalis 

 (fig. 4) . The olfactory bulb is well formed and the fissura prima 

 is begun in the medial wall of the hemisphere. From the ventro- 

 medial surface of the brain at the level of the fissura prima, and 

 therefore behind the olfactory bulb, spring three small roots, two 



