10 OLOF LARSELL 



the brain toward the anterior commissure. The peripheral 

 course of the nerve is described as being in the wall of the sep- 

 tum nasale, along which it passes by several strands to the wall 

 of Jacobson's organ and to a small area of the nasal sac immedi- 

 ately adjacent. 



In the human embryo Johnston found essentially the same 

 central relations as in the pig, but the peripheral distribution is 

 by a network of nerve bundles in the nasal septum. 



He concludes that 'Hhe evidence at present in hand seems to 

 establish beyond doubt the presence in all vertebrates of a re- 

 ceptive component in the nervus terminalis supplying ectodermal 

 territory. This component is derived either from the terminal 

 part of the neural crest (Johnston, '09 b; Belogolowy, '12) or 

 from the olfactory placode (Brookover, '10). The nerve is dis- 

 tributed to the nasal mucosa, or to a specialized part of it, the 

 vomeronasal organ." 



McCotter ('13) demonstrated by dissection the main central 

 bundle of the terminalis in the adult dog and cat. He also found 

 the typical ganglion cells of the nerve distributed along the 

 vomeronasal strands. No differentiation of fibers from those 

 of the vomeronasal nerve was obtained by the staining methods 

 used. 



The application to the problem of a modified pyridin-silver 

 technique by Huber and Guild ('13), served to clearly differenti- 

 ate the terminalis from the vomeronasal nerve. These investi- 

 gators used rabbit fetuses and young rabbits. They were 

 fortunate in securing a differential stain which made it possible 

 to follow the fibers of the two sets of nerves individually. They 

 conclude that 



this nerve is not a component of the olfactory and vomero-nasal com- 

 plex, but an independent nerve, with central connections by means of 

 several small roots to the ventro-mesial portion of the forebrain, caudal 

 to and independent of the olfactory stalk, and courses in the form of a 

 loose plexus along the ventro-mesial surface of the olfactory bulb, 

 reaching the nasal septum and the mesial surface of the vomero-nasal 

 nerve, which nerve it follows to the vomero-nasal organ, and is further 

 distributed to the septal mucosa anterior to the path of the vomero- 

 nasal nerve, in which region especially it is joined by terminal branches 

 of the trigeminus, mainly from the naso-palatine bundles. 



