THE MAMMALIAN' NERVOUS SYSTEM 47 



(b) The composition of the cranial nerves of the dogfish has 

 been considered in Sections 15 to 19, and this should here be 

 reviewed. Even if the laboratory course has not included the 

 dissection of the dogfish, these sections of the Outline should be 

 read at this time. Chapter IX of Herrick's Introduction ('15) 

 should also be carefully read and the general principles of the 

 analysis of the cranial nerves into functional components mas- 

 tered: cf. also Herrick (15), Chapter V, and Sheldon ('18). 

 The components of the cranial nerves of a number of verte- 

 brates have been analyzed microscopically. For an excellent 

 summary and discussion of these studies, which are of funda- 

 mental importance for the proper interpretation of the human 

 nervous system, see Johnston ('06) and ('09). 



(c) Review from the text-books of human anatomy the periph- 

 eral distribution of the cranial nerves, giving especial attention 

 to the classification of the various roots of these nerves into 

 functionally similar groups or systems and the peripheral dis- 

 tribution and mode of termination characteristic of each system. 

 In addition to the references cited in the preceding paragraph the 

 following may be consulted: Bailey ('16), pp. 551, 552; Morris 

 ('14), pp. 927, ff.; Reference Handbook of the Medical Sciences, 

 3d ed., article Cranial Nerves. 



(d) The nervus terminalis. — This is a slender nerve associated 

 with the olfactory nerve which is not described in most text- 

 books of anatomy, for its presence in the human body has very 

 recently been demonstrated. It has long been known in fishes 

 and can readily be seen in a dissection of the dogfish (cf . Section 

 17, 1) . Peripherally this nerve is distributed under the olfactory 

 mucous membrane, but the exact mode of ending has not been 

 determined. Its fibers accompany those of the fila olfactoria, 

 but do not enter the olfactory bulb. In the adult man they pass 

 beyond the olfactory bulb and extend farther backward, usually 

 in several very slender strands embedded in the pia mater over 

 the gyrus rectus, to enter the brain substance at or near the 

 anterior border of the medial olfactory stria. Ganglion cells 

 are scattered along their peripheral course. The intracranial 

 course of the nervus terminalis can usually be seen in a f ormal- 

 inized brain with the aid of a strong magnifying glass. 



For recent descriptions of the mammalian nervus terminalis 



