20 



NUTRITION OF FARM ANIMALS 



and palmitic acids, although small quantities of esters of lauric, 

 myristic and arachnic acids and frequently free fatty acids are 

 also found, as well as minute amounts of esters of the higher 

 alcohols, coloring matter, etc. Since stearin and palmitin are 

 solid at ordinary temperatures, while olein is liquid, the con- 

 sistency of a fat depends largely upon the proportion of olein 

 which it contains and varies not only between different species 

 of animals but often in different parts of the body .of the same 

 animal. The fats of cold-blooded animals contain more olein 

 than those of warm-blooded animals and therefore remain liquid 

 at lower temperatures. 



The vegetable fats contain a greater variety of fatty acids 

 than the animal fats, notably unsaturated acids like linoleic 

 and eruic, as well as oxy-acids and esters of the higher alcohols 

 (waxes), while the so-called crude fat, or ether extract (108) of 

 vegetable materials contains a great variety of ether-soluble 

 substances, including waxes, resins, chlorophyl, etc., some of 

 which are but remotely related to the true fats. 



34. Elementary composition. The three principal triglyc- 

 erids, stearin, palmitin and olein, while differing in formula 

 and molecular weight, differ but little in their elementary com- 

 position, as the following table shows : 



TABLE i. COMPOSITION OF TRIGLYCERIDS 



Naturally, therefore, the composition of the ordinary mixed 

 animal fats varies but little, either in different individuals or in 

 different species of animals. The classic investigations of 

 Schulze and Reinecke 1 upon the composition of animal fats 

 gave the following results. 



1 Landw. Vers. Stat., 9 (1867), 97. 



