INNERVATION OF HEART AND BLOOD-VESSELS 565 



careful not to kill the frog by an overdose of 

 ether. When insensibility is complete, place the 

 animal, back uppermost, on 

 a frog-board. Cut through 

 the skin in the median line 

 from the nose about half 

 way to the urostyle. Care- 

 fully uncover the roof of the 

 skull. Eemove the longitu- 

 dinal muscles on either side 

 of the 1st, 2d, and 3d verte- 

 brae. Strip off the parietal 

 bones with forceps, begin- 

 ning at the anterior end, 

 opposite the anterior margin 

 of the orbit. Clear away 

 the occipital bones. Saw 

 through the laminae of the 

 first three vertebrae, and re- 

 move the laminae to expose Fig. 74. view of the brain 

 the spinal cord. Expose the of a frog from above ' en - 



. larged. L.ol. Olfactory lobes. 



heart by Cutting away the H.C. Cerebral hemispheres. 



chest wall over the pericar- G ' p - Pineal body< Th -- 



A Optic thalami. L.op. Optic 



dlUm. Hold the frog in SUCh lobes. C. Cerebellum. M.o. 



a way that the heart can be Medulla oblon s ata - 



Sinus rhomboidalis. 



observed while the brain and 

 cord are stimulated. With 

 needle electrodes, the points of which should be 



SrA 



S.rh. 

 (After 



Foster's plate in Burdon- 

 Sanderson's Handbook.) 



