96 



PHYSIOLOGY. 



Stimulation of any portion of the intestine causes contraction 

 above the place of irritation, and inhibition or relaxation below the 

 point of irritation. This causes the food to move onward, and is 

 due to Auerbach's plexus. This is the "law of the intestines" accord- 

 ing to Bayliss and Starling. 



Fig. 23. Effect of Albumose, increasing Peristalsis. 



The descending colon has its nerve-supply from two sources: 

 (1) fibers from lumbar nerves to sympathetic chain and mesenteric 

 ganglia, and from the mesenteric ganglia, by fibers running in the 

 hypogastric nerves and plexus; (2) fibers from sacral nerves, run- 

 ning in the nervi erigentes and entering the pelvic plexuses, which 

 are motor and antagonize the preceding fibers, which are inhibitor} 7 . 

 When the small or large intestine is excised, it has peristaltic move- 

 ments, which are due to Auerbach's plexus acting as a reflex center. 



