COMPOSITION OF PLANT AND ANIMAL SUBSTANCES 77 



III. Tannins. 



IV. Glucosides. 



V. Organic acids, salts, and esters. 

 VI. Fats, oils, waxes, and related compounds. 

 VII. Resins. 



VIII. Nitrogen compounds. 



1. Proteins. 



2. Amino acids. 



3. Amines. 



4. Alkaloids. 



5. Purines. 



6. Nucleic acids. 



IX. Pigments. 



1. Chlorophyll — green coloring matter. 



2. Carotinoids — pigments of leaves, stems, flowers, and fruit. 



3. Anthocyanins — pigments of leaves, fruit, and flowers. 



X. Mineral constituents. 



L Bases, especially Ca, Mg, K, Fe. 



2. Phosphates. 



3. Chlorides. 



4. Sulfates. 



5. Silicates. 



The various plant constituents can be divided into the following 

 groups, which are the most extensive and important, since they 

 make up the larger part of the plant and influence the nature and 

 rapidity of its decomposition: 



(1) The water-soluble constituents, including the simple 

 carbohydrates, starches, amino acids, and various organic 

 acids. 



(2) The hemicelluloses, which are condensation products of 

 hexoses, pentoses, or both of these with uronic acids. 



(3) Cellulose, which is a condensation product of glucose. 



(4) Lignin, the exact chemical nature of which is still 

 unknown. It is known to comprise a benzene ring group, sev- 

 eral methoxyl and hydroxyl groups, and an aldehyde group. 

 The following formula is typical for this complex: 



C4oH3o06- (0CH3)-t • (0H)5- CHO 



