130 CHEMISTRY OF PLANT LIFE 



belonging to entirely different chemical groups, which have oily, 

 or fat-like, properties. 



A. FATS AND OILS 

 OCCURRENCE 



Fats and oils are widely distributed in plants. They occur 

 very commonly in the reproductive organs, both spores and seeds, 

 as reserve food material. In fungi, oils are often found in the 

 spores, but sometimes also in sclerotia, mycelia, or filaments. For 

 example, the sclerotia of ergot have been found to contain as much 

 as 60 per cent of oil. In higher plants, many seeds contain high 

 percentages of oil, so as to make them commercial sources for 

 edible or lubricating oils, such as olive oil, rape-seed oil, cotton- 

 seed oil, castor oil, corn oil, sunflower-seed oil, etc., etc. Nuts 

 often contain large proportions of oil, the kernel of the Brazil 

 nut, for example, sometimes contains as high as 70 per cent of oil, 

 while an oil content of 50 per cent, or more, is common in almonds, 

 walnuts, etc. 



Oils also occur as reserve food material in other storage organs 

 of plants, such as the tubers of certain flowering plants, and the 

 roots of many species of orchids. Sometimes the appearance of 

 oils in the stems of trees, or the winter leaves of evergreens, seems 

 to be only temporary and to occur only during periods of very 

 low temperatures. 



Much less frequently, fats or oils are found in the vegetative 

 organs of plants, as in the leaves of evergreens. Their appear- 

 ance and functions in these organs seem to be much less certain 

 than in the other cases cited above; although in rare cases a con- 

 siderable proportion of oily material has been found to exist in 

 definite association with the chloroplasts. 



The vegetable fats and oils have many important industrial uses. 

 Some of them, such as olive oil, cottonseed oil, cocoanut oil, etc., are 

 largely used as human food. Others, as castor oil, are used as 

 lubricants. The so-called " drying oils " (see page 132), such as 

 linseed oil, etc., are used in the manufacture of paints and var- 

 nishes. Some cheap vegetable oils are used as the basis for the 

 manufacture of soaps, etc. Hence, industrial plants and processes 



