436 Animal Biology 



sight, (4) the well-developed midbrain, (5) the small, narrow cerebellum 

 of uncertain function, and (6) the wide medulla oblongata which con- 

 nects with the enlarged portion of the spinal cord. When the brain 

 (except the medulla oblongata) is removed, the frog is still able to 

 breathe, jump, swim, swallow food, and use its sense of equilibrium. 



O/factory tract 

 .Olfactory lobe 



Trigeminus 



facials ^ 

 Auditory 



Optic nerve 



Pineal body 



J)/(2ncephalon 



^pfcic lobe 



CembellurD 



Medulla oblongata 



4y? ventricle 



J?lo550pbaryngeG/ 



Vaqus nerve 



J^ spinal nerve 

 22^ spinal nerve 



Thoracic 

 enlaraement 



Spind cord 



Lumbar. 

 en/argemenb 



.Cerebmm 



} 



Brachial 

 plexuf 



V 3- 5pinal nerve 



.+^ jpinal nerve 



jCalcarsoos body 

 5S?>splnal nerve 



_.6^* ipina/ nerve 



.7^ spinal nerve 



,3 ^-t! spinal nerve 



S— spinal nerve 



lOib ip\na\ nerve 



\ Jciatic pkKus 



Jdatic nerve 



Fig. 216. — Nervous system of a frog (dorsal view). (From Potter: 



Zoology, The C. V. Mosby Co.) 



Filumt^rminale 



Textbook of 



On the ventral side of the brain, the following structures are distin- 

 guishable: (1) optic chiasma, or the crossing of the optic nerves, (2) the 

 hypophysis (pituitary body), and (3) infundibulum. 



