CHAPTER IX 



CONDITIONS INFLUENCING DIGESTION 



THE chemical changes and other phenomena consti- 

 tuting digestion, which have been described as occurring 

 in the alimentary canal, are practically outside the con- 

 trol of the one who feeds the animals. They proceed 

 in accordance with fixed chemical and physiological 

 laws. It is, however, within the power of the feeder 

 to so manipulate the food or vary the conditions under 

 which it is fed that the extent or completeness of diges- 

 tion is modified, and this must be regarded as an im- 

 portant matter when we remember that only the digested 

 food is useful. 



PALATABLENESS 



It is entirely reasonable to believe that a thorough 

 relish for food is conducive to good digestion. The 

 secretion of the digestive juices is not a mechanical 

 process, but is under the control of the nervous system. 

 With man, at least, the enjoyment of eating, even its 

 anticipation, stimulates the secretory power of the sal- 

 ivary glands and those in the mucus lining of the 

 stomach, and it is evident that this holds true with 

 animals. Palatableness is, therefore, an important fac- 

 tor in successful feeding, for it tends to promote a 



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