2 FATS, OILS, AND WAXES 



such as spores and seeds. Not only are the spores, both 

 sexual and asexual of very many Algse and the majority ot 

 the Fungi characterized by the presence of oil, but also the 

 thallus : the filaments of Vaiicheria, for instance, contain much 

 oil ; and of the Fungi, the sclerotia of Claviceps purpurea (ergot) 

 may contain as much as 6o per cent, whilst the mycelium of 

 hactarius deliciosus contains about 6 per cent. 



The fats of the Fungi are rich in fatty acids associated with 

 lecithins and ergosterins. 



In Angiosperms they are widely distributed, especially in 

 seeds where they may replace the carbohydrates as a reserve 

 food-material and are not uncommonly associated with protein 

 reserves ; to mention a few examples, colza oil is obtained 

 from the seeds of Brassica Napus, palm oil from the fruits of 

 Elaeis guineensis, cotton-seed oil from Gossypiuin herbaceum, 

 linseed oil from Linuni usitatissirnunt, olive oil from the sarco- 

 carp of Olea europcea, castor oil from the seeds ot Ricinus, and 

 cacao butter from the fruits of Theobroma. 



Oils of lesser economic importance occur in the fruits or 

 seeds of the sunflower, almond, hemp, willow and many other 

 plants. 



The amount of oil present in such structures may be quite 

 considerable, thus in the kernel of the Brazil nut nearly 70 

 per cent may obtain, and in the almond about 54 per cent. 



Oils also occur in the vegetative organs to a greater or lesser 

 extent ; substances of an oily nature are found in association 

 with the chloroplasts and, in some cases, to a relatively large 

 extent, e.g. in Strelitzia ; sometimes it is present as a definite 

 reserve food-material as in the tubers of Cyperus esculentus, 

 where it is associated with starch, and in the roots of some 

 orchids. 



This particular form of food reserve is doubly of value 

 since its presence may lessen the danger arising from drought, 

 and also more energy can be stored up in the form of oil than 

 in an equal bulk of carbohydrate ; in this connexion may be 

 mentioned the fact that in some cases the appearance of oil 

 may be transient, thus in some trees the starch stored up in 

 the parenchyma of the stem may be converted into fat during 

 the winter's cold ; the starch, however, reappears on a rise in 

 temperature. Also oil may appear in the leaves of evergreen 



