54 PHYSIOLOGY OF ALIMENTATION. 



the ileocsecal valve and along the ileum, for when the valve 

 first allows the food to pass through, it pours into the 

 small intestine and appears as a mass which suddenly fills 

 several loops of the gut. Anti-peristalsis does not appear 

 in the small intestine though it continues in the large. After 

 the food has been in the small intestine for some time, the 

 typical segmenting movements appear, which divide and 

 redivide the food in the manner already described above. 



Figs. 15, 16, and 17 are radiographs which indicate how 

 the food is forced after a large enema more and more from 

 the large intestine into the small. An enema of 90 c.c. 

 was given at 1.40 P.M. The first radiograph shows how 

 at 1.50 P.M. the food is evenly distributed through the large 

 intestine and through several loops of small intestine. In 

 the second and third radiographs, taken at 2.15 and 3.00 P.M. 

 respectively, the food is seen to have left the large intestine to 

 a great extent, and to be occupying an increasingly greater 

 number of loops of small intestine. Observations made at 

 3.00 P.M. showed segmentation to be going on in many 

 of the loops. 



The importance of the ascending and transverse portions 

 of the large intestine as an absorptive organ has already 

 been pointed out, and it is not surprising, therefore, to find 

 evidences of this same absorption when food is introduced 

 into the intestinal tract by way of the rectum. In the 

 region of the anti-peristaltic waves in the large intestine the 

 shadows become progressively lighter, until in the end the 

 bismuth seems to be covering only the walls of the gut. 

 In the descending colon the shadows retain their original 

 opacity. When the rectal injections are large, the small 

 intestine also comes into play as an absorptive organ, and 

 this in the same way apparently as when the food is intro- 

 duced through the mouth. 



It must be pointed out, finally, that if any digestive juices 

 are present in the large and small intestines, these are of 

 course mixed with the nutrient enemas and so are given an 



