THE MAMMALIAN NERVOUS SYSTEM 49 



cerebellum and (for the present) the sulci and gyri of the cere- 

 bral cortex, for the study of which see Sections 114 and 115. 



On the brain of the sheep see Figs. 7 to 12, and for additional 

 illustrations consult Burkholder ('12) and Fiske ( r !3); for the 

 human brain consult any standard text-books. 



47. The cranial nerves. (a) Locate on both the sheep and 

 the human brains the roots of the twelve pairs of cranial nerves. 



(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 ('18) 

 should also be carefully read and the general principles of the 

 analysis of the cranial nerves into functional components mas- 

 tered: cf. also Herrick ('18), Chapter V. The components 

 of the cranial nerves of a number of vertebrates have been 

 analyzed microscopically. For an excellent summary and 

 discussion of these studies, which are of fundamental impor- 

 tance for the proper interpretation of the human nervous sys- 

 tem, see Johnston ('06) and ('09). 



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

 peripheral 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 

 distribution 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 associ- 

 ated 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 



