Why Digestibility Varies 125 



fats and oils are quite completely emulsified and ab- 

 sorbed. 



The foregoing statements make it plain that when 

 the general composition of a feeding stuff is known it- 

 is possible to predict with a good degree of certainty 

 whether its rate of digestibility is high or low. The 

 larger the proportion of starch and sugar and the smaller 

 the percentage of gums and fiber, the more complete 

 will be the solution. We see this illustrated in the ex- 

 treme by the difference in digestibility of corn meal and 

 of wheat straw. 



NOTE. Compounds that have been digested and absorbed into 

 the alimentary canal may be excreted in the feces. Bergman 

 showed that when a compound of phosphoric acid was injected 

 subcutaneously into sheep, the phosphoric acid was excreted in 

 the dung. According to Mendel and Thacher, mineral compounds 

 absorbed from the intestinal tract may afterwards appear in the 

 feces. Recent observations appear to show that phytin, a phos 

 phorus body, is absorbed, metabolized and its phosphorus subse- 

 quently excreted in the feces in inorganic combinations. 



