28 



THE FROG 



which lies a white rod, made of the same soft, pulpy 

 substance as the nerves, and called the spinal cord 

 (sp. cd\ which ends behind in a thread-like prolongation 

 (/ /), some distance in front of the thighs. It will also be 

 found that the neural canal is continued, with a slightly 



ust. 



FIG. 6. Dissection of a Frog in which the entire neural canal (.<:.) has been opened 

 from above, and the brain (br) and spinal cord (sp. cd) laid bare. The brain con- 

 sists of olfactory lobes (olf. 1), cerebral hemispheres (crb. /?), diencephalon (dien), 

 optic lobes (opt. /), cerebellum (cl>lm), and medulla oblongata (med. obl\ which 

 will be referred to in Chapter X. The spinal cord ends in a delicate prolonga- 

 tion, the filum terminate (f. f). The nasal bones (na\ eyes (e), auditory 

 region of the skull (au), transverse processes of the nine vertebrae (v. I v. 9), 

 urostyle (u. st) and ilia (il) are indicated in outline, and serve as landmarks. 



^ fAfter Howes, slightly altered.) 



increased diameter, into the skull, and that the spinal cord 

 becomes continuous with the brain (br), a complex organ 

 formed of several parts, which will be referred to hereafter. 

 General Structure of the Limbs. A transverse section 



