234 A MANUAL OF VETERINARY PHYSIOLOGY 



In the ox the amount of faeces is between 32 kilogrammes 

 (70 pounds) and 37 kilogrammes (80 pounds) in the twenty-four 

 hours. In the sheep it varies from 1 to 3 kilogrammes (2 to 6 

 pounds) daily; in swine ij to 3 kilogrammes (3 to 6 pounds), 

 depending on the nature of the diet. 



The odour of faeces is distinctly unpleasant, due to the presence 

 of indol and skatol ; in disease they are often extremely foetid, 

 and occasionally horrible. 



\The act of defaecation is performed by a contraction of the 

 rectum, assisted by the abdominal muscles, the glottis being 

 closed./ In the horse the contraction of the rectum alone is 

 sufficient to expel its contents ; this is proved by the fact that this 

 animal can defaecate while trotting, showing there is no necessity 

 to fix the diaphragm and hold the breath, though at rest this does 

 occur. In consequence the rectum of the horse can exercise 

 extraordinary power ; the hand and arm may be rendered almost 

 numb by the pressure it can exert. The mass driven backwards 

 under this force causes the sphincters to dilate, sometimes to an 

 astonishing degree, and as the last trace of material is extruded, 

 the contraction of the rectum is so great that it forces some of 

 the mucous membrane externally, which may be temporarily 

 imprisoned by the contracting sphincters. The muscle of the 

 rectum receives both motor and inhibitory fibres, as previously 

 described. Its extraordinary power in the rectum of the horse 

 may partly be due to the horizontal position of the body ; no 

 crouching of the body occurs during the act of defaecation, such 

 as occurs, more or less, with all other domesticated animals. 

 The rectum has the whole work to perform single-handed, even as 

 we have shown above, without the assistance of the diaphragm 

 or abdominal muscles. 



Two sphincters close the rectum in all animals — an external of 

 voluntary and an internal of involuntary muscle ; they are pre- 

 sided over by a centre in the cord. If this is destroyed, the 

 rectum remains uncontracted, and the sphincter flabby ; in the 

 dog the cord may be destroyed in the lumbar region without 

 interfering with the act of defaecation, which is then carried on 

 by a reflex mechanism. 



Meconium is the dark green material found in the intestines of 

 the foetus. It consists of biliary acids and pigments, fatty acids 

 and cholesterin, while salts of magnesium and calcium, phosphates 

 and sulphates, sodium chloride, soda, and potash are also found 

 in it. Meconium is the product of liver excretion. 



Pathological. 



The diseases of early life in the horse are mainly situated in the 

 chest, while those of the adult period arc practically confined to the 

 abdominal viscera, principally the intestines. The term ' colic ' 



