98 ' 



ELEMENTARY PHYSIOLOGY. XIX. 



exit from the vertebral canal, and isolate it for a short 

 distance. 



10 



Fig. 28. Diagram of abdominal sympathetic of the frog. The numbers 

 on the left refer to the spinal nerves and are placed opposite their 

 exit from the vertebral column; the usual position of their junction 

 with the rami communicantes are shown. 



Watching the thin walled bladder, and the rectum, 

 stimulate the nerve. The bladder will contract, and the 

 rectum will probably be drawn downwards. (There is 

 generally some spontaneous contraction of the rectum, 

 each contraction lowers the irritability for a time.) In 

 some frogs the 10th nerve is larger than the 9th instead 

 of being barely visible; in these the 10th nerve causes 



