24 



THE FROG 



(g) The brain and spinal cord can now be removed from the 

 animal. Insert a scalpel under the spinal cord toward its posterior end 

 and lift it carefully. Cut any membranes or nerve roots that tend 



opt/c C^/a5/7?0> 

 hc/pophL/3/s 



sp/na/ co^d 



commun/cone 



5{//npcfi/?et/c 

 nerwe 



Si/f77po't/7ei/c 

 ga/7g//o/7 



f//U/77 



term/na/e. 



nasa/ cav/iy 

 o/foctorc/ ner^^e (I) 



~ 6roc/?/a/ nerv^C' 



Fig. 22. — Nervous system of the frog, from ventral view. J-X, cranial nerves; 



1-10, spinal nerves. 



(Redrawn from R. Wiedersheim, "Comparative Anatomy of Vertebrates," copyright, 1907, 

 by Tlie Maciiiillan Co., printed by iKTiuissioii.) 



to hold it in place, working toward the anterior end. In the region of 

 the brain cut the optic nerves. Note the hypophysis, or pituitary 

 gland, which is attached to the brain; this is a gland, not a part of 

 the central nervous system. It can be lifted out with the brain. 



