344 INTRODUCTION TO BOTANY 



C 6 H 1Q O 5 , and in making this unit of starch there has been used 

 all of the carbon, all of the hydrogen, and five units of the 

 oxygen, thus leaving twelve units of oxygen to be set free or 

 to be used by the plant in some other way. Some of this free 

 oxygen passes into the air, though some of it is used by the 

 plant in a later process. 



The compounds thus constructed, such as starch and sugar, 

 are called carbohydrates, the name indicating that they are 

 compounds of carbon and water. 



