46 MAKUAL OF OATTLE-FEEDIKG. 



By long-continued boiling, all these bodies are eonrertcd 

 into nietapectic acid, wliiclx is quite soluble and liafo a bour 

 taste. 



All tliese bodies are digestible, and are not unimportant 

 as nutrients. Tliey probably play mucli the same part in 

 nutrition as the carbhydrates. 



The Fats. — Composition. — The fats found in plants 

 have essentially the same composition as that possessed by 

 those occurring in the animal body, and already noted on 

 page 12, viz., on an average : 



Caibon , 76 5 per cent. 



Hydrogen. 13.0 *' 



Oxygen 11.5 " 



ioo7o 



It will be noticed that these nutrients differ from j:hose 

 hitherto considered in containing a much larger proportion 

 of carbon and a much smaller one of oxygen. They con- 

 sequently require much more oxygen for their complete 

 combustion and give out about two and one-half times as 

 much heat in binning as the caihhydrates, a fact of great 

 importance in connection with the production of animal 

 heat, and which will be treated of more fully in a subse- 

 quent chapter. 



Oeourrenee.— Fat is found in small quantities in almost 

 all plants. 



In roots we find 0.1 to 0.2 per cent. ; in hay and straw, 

 1.0 to S.O per cent. ; in the cereal grains, 1.5 to 3.0 per 

 I3efit., except in oats, which contain as much as 6 per 

 cent. ; and in maize about 4 to 9 per cent. It is especial- 

 ly, however, in the seeds of certain plants that fat or oil 

 occurs. 



The seeds of flax, hemp, colza, cotton, and numerous 



