m 



DIGESTION 



which will be made clear by consulting Fig. 161. This rhythmic scg- 

 mentation, as Camion lias called it, continues without cessalion for more 

 than half an hour, and the food shadow does not meanwhile seem to change 

 it s position in the abdomen to any extent. The splitting up of the seg- 

 ment and the rushing together of the neighboring halves proceed as a 

 rule with great rapidity; thus, if we counl the number of different se.^- 



Elasric rubber 

 band to attach 

 finqer cot to 

 'cdtfiekr 



IfiO. — Apparatus fur recording contractions of the intestine. (From Jackson.) 



meiits during a definite period, we may find the rate of division in the 

 eat to he as high as 28 or 30 a minute. In man the divisions occur at a 

 frequency of approximately 10 per minute, which corresponds to the fre- 

 quency with which sounds can lie heard when the abdomen is auscultated. 

 Although half an hour is the period which this process usually oc- 

 cupies, ii may last considerably Longer. In certain animals, such as the 

 rabbit, segmenting movements have not been observed, hul instead 



