2 FATS, OILS, AND WAXES 



amount of fat. Amongst the Protophyta, fat is the charac- 

 teristic food reserve of the Heterokontae, Chrysophycese, 

 Bacillariales, and Chloromonadales. In the Phaeophyceae, the 

 amount of fat, or fat-Hke substances, would appear to vary 

 with the conditions of Hfc. Thus Pelvetia canaliculata, var. 

 libera, which is submerged only during the spring tides, may 

 contain 8 per cent of ether-soluble material, whilst Laminaria 

 digitata, which is exposed only at low water of spring tides, 

 contains but 0-5 per cent. The fucoids of the intermediate 

 zones contain amounts of ether-soluble substance intermediate 

 between these extremes. The Rhodophycese which are charac- 

 teristic of the submerged zone would appear to contain less 

 fat, thus Chondrus crispus yields 0*2 per cent of ether-soluble 

 material.* The fats of the Fungi, which are rich in fatty acids 

 associated with lecithins and ergosterols, vary much in amount; 

 thus the sclerotia of Claviceps purpurea (ergot) may contain 

 as much as 60 per cent, whilst the mycelium of Laclarius 

 deliciosus contains about 6 per cent. 



In Angiosperms fats 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 pericarp 

 of the fruits of Elceis guineensis , cotton-seed oil from Gossypium 

 herbaceum, linseed oil from Linuni usitatissimum, olive oil from 

 the sarcocarp of Olea europcea, castor oil from the seeds of 

 Ricinus, and cacao butter from the fruits of Theobrotna. 



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 sueh 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 



* Authors' observations hitherto unpublished. 



