NERVUS TERMINALIS: MAMMALS \) 



esses, of which one in each case enters the 'ramus olfactorius 

 nervus trigemini.' Cells of this type are relatively few in num- 

 ber. These observations have been interpreted by some writers 

 to indicate the presence of the nervus terminalis in birds. 



Mammals. Since 1905 the nervus terminalis of mammals has 

 been dealt with in no less than nine scientific memoirs. In some 

 cases it has been confused with the fibers of the vomeronasal nerve 

 (Devries, '05; Dollken, '09), but in most cases the fibers of the 

 terminalis are distinguished from those of the vomeronasal. 

 Notwithstanding these investigations, the nervus terminalis in 

 the mammals is very imperfctly known and its relations are 

 obscure. 



■ The first published notice of this nerve in the mammals was 

 made by DeVries in 1905. He found in the human fetus of three 

 to four months a transitory ganglion which he regarded as cor- 

 responding to the ganglion of the nervus terminalis, and which 

 he designated 'ganglion vomero-nasale.' He also found similar 

 conditions in the guinea-pig. His assumption that the vomero- 

 nasal nerve of mammals represents the nervus terminalis of 

 selachians and other fishes is not substantiated by more recent 

 work. 



Dollken ('09) studied embryonic stages of rabbit, mouse, guinea- 

 pig, pig, and human. His account of the central connections of 

 what he describes as the nervus terminalis is extended. He finds 

 roots which enter the brain and reach the cortex, the gyrus forni- 

 catus, the hippocampus, and the septum pellucidum. The pe- 

 ripheral distribution he describes as being by four or five strands 

 to the vomeronasal organ. It seems clear from his description 

 and figures that he is dealing almost entirely, if not completely, 

 with the vomeronasal nerve, which Read ('08) and McCotter ('12) 

 have clearly differentiated from the olfactory fibers proper in 

 mammals, and McCotter ('17) in the turtle and the frog. 



In a paper already referred to in connection with the nervus 

 terminalis in reptiles, Johnston ('13) also describes the nerve in 

 embryos of pig, sheep, and human. In pig embryos he finds the 

 root of the terminalis entering the brain at the ventral end of the 

 fissura prima. The fibers are traceable for some distance within 



