90 FATS AND ALLIED SUBSTANCES [ch. 



Another series is the oleic or acrylic series CnHgn-aOa of which the 

 members are: 



Tiglic acid CsHyOa 

 Oleic acid C18H34O2 

 Elaidic acid C18H34O2 

 Iso-oleic acid C18H34O2 

 Erucic acid C22H42O2 

 Brassidic acid C22H42O2 



Of these, oleic acid (as glyceride) is the most widely distributed. 



Yet other series are: 



The linolic CnH2„_402 



The linolenic C„H2,i_602 

 The clupanodonic C„H2„_802 

 The ricinoleic C„H2„_203 



The fat which occurs in an oil-containing seed is not composed of the 

 glyceride of one acid, but is a mixture of the glycerides of several, or 

 even a large number of different acids, often members from more than 

 one of the above series. Thus the fat of the fruit of the Coconut (Cocos 

 nucifera) consists of a mixture of the glycerides of caproic, caprylic, 

 Capric, lauric, myristic, palmitic and oleic acids. Linseed oil from the 

 seeds of Linum usitatissimmn again, is a mixture of the glycerides of 

 palmitic, myristic, oleic, linolic, lin"6lenic and isolinolenic acids. Similar 

 mixtures are found in other fruits and seeds. 



Since glycerol is a trihydric alcohol, it would be possible for one or 

 more of the three hydroxyls to react with the acid to form mono-, di- or 

 tri-glycerides. All these cases occur and, sometimes, one hydroxyl is 

 replaced by one acid, and another hydroxyl by a different acid. 



When the distribution of fats among the flowering plants is con- 

 sidered, they are found to be more w^idely distributed than the botanist 

 is generally led to suppose. 



The following is a list of some of the plants especially rich in fats as 

 reserve material in the fruits or seeds. It represents only a selection of 

 the better known genera, since many other plants have fatty seeds. An 

 approximate percentage of oil present in the fruit or seed is given. 



Gramineae: Maize {Zea Mays) 4 7o- 



Palmaceae : Oil Palm {Elaeis guinensis) 62 "/^^ : Coconut Palm (Cocos 

 nucifera) 65 7o- 



Juglandaceae : Walnut (Juglans regia) 52 Yo- 

 Betulaceae: Hazel {Gorylus AvelUma) 55 "/o- 

 Moraceae : Hemp {Cannabis sativa) 33 7o- 

 Papaveraceae : Opium Poppy (Papaver somniferum) 47 ^/o- 



