136 INTESTINES CONSTRUCTION [BOOK I. 



overphysicking, in the disgusting protrusion of the 

 inner coat whilst expelling the contents thereof; 

 an ordinary effort of nature to get rid of what is 

 offensive to it, which, considering the horizontal 

 position of the horse, might appear wonderful to 

 us bipeds but for the well-known double operation 

 of the coats of the intestines. From the top to the 

 bottom of the canal a spiral motion is kept up by the 

 alternate contraction of the two coats thereof, the 

 one in circumference, the other lengthwise, resem- 

 bling that of a worm, and appearing as if a cork-screw 

 agitated its inside. By this means the mass is 

 pressed backwards, and as it increases in quantity 

 and becomes less and less clearable, the offended 

 nerves excite the guts to renewed efforts for its ex- 

 pulsion, in which the lower part of the belly, with 

 its covering, from the ccecum to the sphincter, con- 

 cur with all their powers of contraction. Partial 

 retention of the breath, and consequent pressure 

 upon the midriff, and parts behind it, contribute to 

 lessen the longitude of the intestine at every effort. 

 This kind of excitement, if repeated too often, it is 

 plainly to be seen, must keep up the irritation of 

 the parts concerned in it inordinately, and dispose 

 them to contract inflammation. 



48. In length about thirty yards, the intestinal 

 canal has in its course two or three different offices 

 to perform towards digestion, whereof the smallest 

 gut nearest the stomach is for receiving the gall, 

 or bile that has been formed in the liver for that 

 purpose. At the termination of the next small gut, 



