Neural Integration 179 



layer of the stomach and small intestine to produce "tone" is 

 increased on the whole by the cranial autonomic, while gas- 

 tric peristalsis and secretion are inhibited and the arterioles 

 of these organs are contracted by the thoracico-lumbar. 11 

 The pupil of the eye is contracted by the cranial autonomic 

 and dilated by the thoracico-lumbar. The lower part of the 

 large intestine is contracted by the sacral autonomic and is 

 relaxed by the thoracico-lumbar. The discharge tube of 

 the urinary bladder is relaxed by the sacral and contracted 

 by the thoracico-lumbar. The blood vessels of the erectile 

 tissue of the external genitals are dilated by the sacral 

 autonomic and contracted by the thoracico-lumbar; and 

 so on. 



Now it is especially important, as Cannon says, to notice 

 the kind of service these subdivisions of the autonomic sys- 

 tem perform for the organism. On considering the func- 

 tions of the cranial division, one recognizes that they have 

 to do with bodily conservation. "By narrowing the pupil 

 of the eye they shield the retina from excessive light. By 

 slowing the heart rate, they give the cardiac muscle longer 

 periods for rest and invigo ration. And by providing for the 

 flow of gastric juice and by supplying the muscular tone 

 necessary for contraction of the alimentary canal, they 

 prove fundamentally essential to the processes of proper 

 digestion and absorption by which energy-yielding material 

 is taken into the body and stored. To the cranial division 

 of the visceral nerves, therefore, belongs the quiet service 

 of building up reserves and fortifying the body against times 

 of need or stress." 19 



Pasing to the sacral division, one sees that as concerns 

 its distribution to the digestive and urinary viscera, its of- 

 fice is that of accomplishing the discharge of refuse material 

 from the body. Hence, "like the cranial division, the sacral 

 is engaged in internal service to the body, in the perform- 

 ance of acts leading immediately to greater comfort." 



