140 



THE CHEMISTRY OF THE PLANT 



Carbonic 

 H2CO3 



Silicic (of various forms) 

 Si(0H)4, etc. 



Organic Acids. 



As CaCOs in cyst olit lis of 

 Ficus, and as deposits in or 

 upon the cell walls of many- 

 algae and fungi. 

 These are absor])ed in the K, 

 Na and Al salts and are some- 

 times deposited in undeter- 

 mined composition in cell 

 walls, e.g. diatoms, scouring 

 rushes (Equisetum), etc. 



These occur in all parts of the 

 plant, either free or as esters 

 or as salts of metallic bases. 

 They are present as reserve 

 food, as waste products, as 

 substances to increase the os- 

 motic pressure, to increase 

 acidity, etc. 



As free acid in stinging hairs 

 of nettles, in some fruits, etc., 

 and sometimes as salts of 

 various metals. 



As salts of various metals in 

 the cell sap. Formed as free 

 acid by the fermentation of 

 ethyl alcohol by various bac- 

 teria. Produced in dry distil- 

 lation of wood. 



Butyric (normal) As esters in various Apiaceae. 



C4H8O0, (CH3-CH2-CH.2- 



COOH). 

 Isobutyric Free in fruit of St. John's 



[ CHsv bread {Ceratonia siliqua) and 



C4H8O2, \ >CH-COOH)in various other plants. 



[ cn/ 



Palmitic, Stearic and Oleic (see below under /«/s). 



Glycollic In unripe fruits and leaves of 



C2H4O3, (CH2(OH)-COOH) the grape. 



Formic 



CH2O2, (HCOOH) 



Acetic 



C0H4O2, (CH3COOH) 



