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MANUAL OF PHYSIOLOGY. 



cavity of a recently killed animal is opened depends partly on 

 the exposure to cool air, and partly on the venous character of 

 the blood in the vessels no longer oxidized by respiration. 



The irregular and impetuous action of the intestine which 

 follows the constriction or strangulation of a hernial protrusion, 

 chiefly depends on the mechanical effect, but also is probably 

 intimately related to the interference with the blood supply con- 



FIG. 55. 



Diagram of a longitudinal section of the wall of the small intestine. ft. 

 Villi. 6. Lieberkiihn's glands, c. Muscularis mucosse, below which lies 

 Auerbach's nerve plexus, d. Connective tissue in which many blood and 

 lymph-vessels lie. e. Circular muscle fibres cut across, with Meissner's nerve 

 plexus below. /. Longitudinal muscle fibres, g. Serous coat. 



sequent on the pressure exerted by the constricting baud. Pro- 

 longed over-work often induces immobility of the intestinal wall, 

 and hence we find the purging and vomiting, which accompany 

 a temporary hernial constriction, followed by inability of the 

 intestine to propel its contents. These points have also been 

 proved by results of experiments on the lower animals. 



The movement of the large intestines are the same as the small, 

 but not so obvious, owing to the modified sacculated shape of this 

 part of the alimentary canal. The contractions of the colon begin 

 at the ileo-csecal valve where the peristaltic wave of the ileum 

 ceases. The normal intestinal motions thus pass in an almost 

 uninterrupted wave from the pylorus to the end of the gut, but 

 when special sources of irritation exist, a wave may originate in 



