92 The Feeding of Animals 



has parted from the glycerine with which it was origi- 

 nally combined in the milk. In plant oils, on the other 

 hand, are found considerable proportions of the free 

 fatty acids, some of which have not been discovered so 

 far in animal fats, either free or uncombined. 



Perhaps no one has studied plant oils more thor- 

 oughly than Stellwaag, who investigated the ingredients 

 of the ether and benzine extracts from plants. His 

 results show that not only do these extracts include 

 substances which are not fats, but that a considerable 

 proportion of free fatty acids is always present, some- 

 times in quantities exceeding the neutral fats: 



Composition of ether -extracts (per cent) 



Neutral Free fatty Material not 

 fats acids saponifiable 



Hay 23.7 37.3 30.8 



Malt sprouts 24.7 30.1 34.5 



Potatoes 16.3 56.9 10.9 



Beets 23. 35.3 10.7 



Maize, kernel 88.7 6.7 3.7 



Barley 73. 14. 6.1 



Oats 61.6 27.6 2.4 



It appears, as before stated, that ether -extract, es- 

 pecially that from coarse fodders, may consist, to a large 

 extent, of materials which should not be classed among 

 the fats. Stellwaag demonstrated that only about 60 

 per cent of the hay extract which he investigated con- 

 sisted of oil. On the contrary, the extracts from the 

 grains proved to be nearly all oil. Moreover, the grain 

 oils were made up principally of glycerides, and those 

 from hay, malt sprouts, potatoes and beets consisted 

 largely of free fatty acids. 



