250 THE COMMON COLICS OF THE HORSE 



bulk of the wall consists of circular muscle only. The longi- 

 tudinal bands shorten the bowel, but the main work in press- 

 ing the contents along is performed by the circular layer. 

 The bands, in fact, are numerous where the intestine is large, 

 and reduced in number where the bowel becomes smaller. 

 This arrangement suggests that they may, under suitable con- 

 ditions, produce an irregularity of pull, and we can see no other 

 explanation of displacement of the large intestines of the horse 

 than through the medium of these muscular bands. 



' The muscular movements of the large intestine are slower 

 than those of the small bowels. Possibly one reason for this 

 Flexures : 

 Sternal Pelvic Diaphragmatic 



From -a V' =; \ To 



— ^'-^* =:^^ = ■ j T -^jie 



6* 'J Colon 



lat Colon ! 2nd Colon ; 3rd Colon ; 4tli Colon 

 • • ; 



Fig. 21. — Schematic Arrangement of the Mdscular Bands 

 ON the Double Colon. 



The colon is supposed to be opened out into a straight tube. 

 Bands i, 2, and 3 run from the first colon to the pelvic flexure ; 

 one of the three actually comes from the apex of the caecum. 

 No. 4 is the only band running the whole length of the bowel. 

 Nos. 5 and 6 originate in the region of the third colon, and 

 finally run on to the single colon. (Smith's ' Veterinary 

 Physiology.') 



may be that the food has to remain a longer time in contact 

 with the absorbing surface — viz., for at least forty-eight hours, 

 and for as long as four days. The peristaltic movement of the 

 small intestines is quite distinct from that of the large ; the one 

 ends at the ileum, the other begins at the cjecum. 



' The muscle of the intestinal wall causes the movement 

 known as "peristalsis," which normally passes in the direction, 

 stomach to rectum. Relatively quick in the small intestines, 

 it becomes slower and more deliberate in the large ; but the 

 wave has always the one object in view — viz., to press the 

 ingesta onward. A wave of contraction passing the reverse 

 way — viz., in the direction of rectum to stomach — is known as 



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