DIGESTION IN THE INTESTINES. 87 



prevents it from becoming absorbed ; the result being that 

 the nitrogenous matter becomes putrid, and consequently 

 imparts a foul smell to the dung (Bunge). Colin estimates 

 that a horse secretes daily about one-sixty-sixth of his weight 

 of bile. This secretion contains from 82 to 91 per cent, of 

 water ; various salts, chiefly of soda ; fatty matters ; and 

 colouring matters. 



The liver constantly secretes bile, which in men, cattle, and 

 in the large majority of other mammals, flows into a reservoir 

 (gall bladder) and from thence issues into the small intestine. 

 As horses were found to have no gall bladder, and as they 

 were known to feed more or less continuously when at grass, 

 it was generally inferred that the absence of a gall bladder 

 in a horse was a proof that he should be fed at frequent 

 intervals of time. Although the conclusion was true, the 

 premises of the argument were incorrect ; because the 

 possession or non-possession of a gall bladder appears to 

 have no connection with the digestion of food. For instance, 

 among ruminants we find that deer, camels, and llamas have 

 no gall bladder. This reservoir is also absent in ostriches, 

 parrots, guinea fowl, and pigeons (Colin), though present in 

 most other species of birds. Besides, the possession of a gall 

 bladder does not prevent the continued flow of bile into the 

 small intestine, whether the food is or is not passing through 

 that portion of the alimentary canal. 



On leaving the small intestine, the food and water become 

 collected in the caecum, which acts to some extent as a 

 supplementary stomach. In it and in the greater portion of 

 the remainder of the large intestine, the processes of digestion 

 and absorption are continued, until finally the unappropriated 

 residue in the form of dung is expelled. The digestive 

 power of the lower portion of the large intestine is feeble. 

 The intestinal juice has the property of dissolving carbo- 

 hydrates and nitrogenous matter. In the horse, a portion 



