56 THE STORY OF PLANT LIFE 



lignocelluloses found in woody tissues. Inulin is of 

 the same composition as starch, and found in many 

 of the Compositae, as in the DahHa and Chicory roots, 

 Bellflower group, etc., in bulbs of LiHaceae, etc. 



In addition to carbohydrates there are fats and 

 fixed oils, made up of compounds of glycerine and fatty 

 acids with less oxygen than in the first group. They 

 occur in the cell matter as drops, and in reserve 

 materials, found largely in endosperm and the young 

 seed leaves, and in fruits. 



A third group consists of volatile or essential oils 

 which are the basis of the perfumes of flowers, as in 

 the rose. Some are made up of carbon and hydrogen, 

 without oxygen, but in others the last is present. 

 They occur in the same form as the fats and fixed 

 oils, and may be developed in connection with glands 

 or other accessory structures. 



Many organic acids are found in plants, such as 

 malic, oxalic, citric, tartaric acid, etc., and are either 

 free or combined. A common example is Sorrel, in 

 which binoxalate of potash occurs. Crystals of 

 calcium oxalate also occur, as single crystals; in 

 needle-like bundles or raphides, etc. 



The nitrogenous organic substances include those 

 that are built up of carbon, hydrogen and oxygen, 

 and also of nitrogen, with sulphur, and phosphorus. 



The proteids or albuminoids are slimy and coagu- 

 late when warmed, and are found in connection with 

 the protoplasm of the cell, being present in all parts of 

 a plant. Some are employed as reserve materials as 



