COMPOUNDS OF NUTRITION 45 



Potash is much less pBominent in the composition of 

 the animal than is the case with plants, and phosphoric 

 acid and lime are much more so. In general, more than 

 80 per cent of the ash of the animal body consists of phos- 

 phoric acid and lime in combination as calcium phosphate, 

 whereas these two compounds constitute less than one- 

 fifth of the ash of hay and less than one-half of the ash 

 of maize and wheat kernels. 



56. The distribution of inorganic compounds in the 

 animal body. — ^The bones contain a very latrge proportion 

 of the ash constituents found in. the animal body, the soft 

 parts being poor in mineral salts. Between 60 and 70 

 per cent of the ash comes from bone, and the bony frame- 

 work is from 6 to 9 per cent of the entire bodies of domes- 

 tic animals. WilUams and Emmett found that the total 

 ash in the bodies of pigs forty to forty-three weeks old 

 was distributed among the parts as follows: about four- 

 fifths in skeleton, one-ninth in the boneless meat and 

 about one-sixteenth in the offal, blood, and the jowl and 

 intestinal fats. Of the water-soluble ash, only about one- 

 twelfth was found in the skeleton, with about three-fifths 

 in the boneless meat. This distribution of the ash was not 

 the same in pigs forty to forty-three weeks of age as for 

 pigs eighteen weeks of age. The offal and carcasses of 

 the younger animals contained practically twice as much 

 as those of the older pigs, while the skeletons contained 

 only about three-fourths as much. More than 80 per 

 cent of the ash of bone is calcium phosphate, which is 

 associated with calcium carbonate, calcium fluoride, cal- 

 cium chloride, and magnesium phosphate. 



The bones of all species of animals show a remarkable 

 similarity of composition, the average of which would not 

 be far from the following: 



