BIGGEST AND BUSIEST FACTORY 203 



or peristaltic waves commence which carry the liquid 

 chyme slowly towards the caecum. We have seen that 

 the average rate of progress is only about one inch a 

 minute. 



These driving peristaltic waves, however, do not 

 represent the true beat or pulse of the intestinal muscu- 

 lature. The chyme has not only to be carried along the 

 bowel, it has also to be kneaded and broken so that new 

 surfaces are being continually brought in contact witty 

 the living membrane. It is only by exposing fresh 

 particles of chyme to the wall of the bowel that the 

 digestive juices and absorbing surfaces can accomplish 

 their purposes. Hence we find that the musculature of 

 the bowel, besides being thrown into occasional driving 

 waves, is always contracting rhythmically, as if it were 

 a heart ; constantly kneading and moving the chyme, and 

 at the same time producing another but very important 

 effect — squeezing the capillary field of the lining mem- 

 brane and thus helping to drive the blood, laden with the 

 products of digestion, into the portal vein and liver. 

 Our health depends very greatly on the soundness and 

 activity of the transport system of the small bowel. If 

 the chyme stagnates, then it also ferments and putrefies. 



The contraction waves always go in one direction — 

 down the bowel. The mechanism which prevents them 

 from passing in the opposite direction we are not quite 

 certain of. There are nodal points at the beginning of 

 the small bowel, and these, being more excitable than 

 the musculature lowef down, dominate the rest of the 

 bowel and become the pace-makers of its transport system. 

 Contraction waves, however, may become reversed. If 

 an obstruction should occur in the passage of the chyme 

 then waves arise at the site of the obstruction and sweep 

 upwards, milking the chyme away from the point of 

 blockage. That is Nature's mechanism for affording 

 relief and at the same time producing the conditions 

 which will permit a cure to be effected. Although the 

 movements of the bowel arise within its own musculature, 

 yet the central nerve system has access to it and can 



