414 



A TEXTBOOK OF PHYSIOLOGY 



During digestion, the acidity of the contents causes the .closure of the 

 sphincter to become firmer. When the stomach is very full, and there 

 is no acidity of the reservoir contents, rhythmic relaxation and contrac- 

 tion of the cardiac orifice may occur, with the result that the stomach 

 contents are regurgitated into the oesophagus. This has been ex- 

 perimentally demonstrated on cats both by the X-ray method and 



FIG. 209. DIAGRAM REPRESENTING THE PROCESS or RHYTHMIC SEGMENTATION. 



(Cannon.) 



Lanes 1, 2, 3, 4, indicate the sequence of appearance in a single loop. The dotted 

 lines represent the regions of division. The arrows show the relation of the 

 particles to the segments they subsequently form. 



by direct registration by means of a tambour placed in the oesophagus. 

 The addition of acid immediately caused a cessation of such move- 

 ments (Fig. 208). 



That such a regurgitation occurs in man has been proved by the 

 fact that lycopodium spores swallowed overnight in a gelatin capsule 



FIG. 210. PHOTOGRAPH OF THE SMALL INTESTINE SEGMENTING ITS CONTENTS. 



(Cannon.) 



have been found in the mouths of persons next morning, although 

 there was no trace of them in the mouth one to two hours after swal- 

 lowing. It is suggested that the disagreeable taste in the mouth and 

 the coated tongue of the dyspeptic may be due in part to particles of 

 food regurgitated from the stomach, especially when there is a de- 

 ficiency of hydrochloric acid in that organ. 



