PLANT PRODUCTS 



137 



(mannaiis and galactans) which are very similar to true cellu- 

 lose. They are deposited on the inner surfaces of the walls of 

 cells and are very readily transformed into sugars. They give 

 the hard, horn-like character to coffee and date seeds and are im- 

 portant foods in the germination of these f^eeds. 



The alkaloids are supposed to be formed in tlio protoplasm, 

 but are later found in the cell sap in combination with the vari- 

 ous plant, acids. They contain nitrogen, e;n-bon, hydrogen and 

 sometimes oxygen; they will cpnibine with acids and form salts. 

 They are usually 

 associated with 

 sitai'ch, fixed oils, 

 aleurone grains 

 and Cither reserve 

 food products. 

 They may be 

 abundant in im- 

 mature fruits and 



J 1. -f j-l, Fi«, 94. — Cell from ^laia of corn containing starch, 



disappear with maturity, llany of the alkaloids are very poi- 

 sonous. Among the most important are the following: 



(a) Theine, from tea; 1 to 3 per cent, in dry leaves. 



(b) Cajfeine, from coffee ; .5 to 2 per cent, in the bean. 



(c) Theohromine, from tacao, or chocolate plant; 1.5 per 

 cent, in the seeds. 



All of the above are in general use, but are poisonous and 

 injurious to health when used in large quantities. 



(d) Morphine and a number of other alkaloids from the 

 opium poppy are used in medicine. The smoking of opium has 

 most deleterious effects on both body and mind. Opium and its 



