48 CORN CROPS 



may be illustrated as follows, leaving out intermediate 

 steps : — 



6 CO2 + 6 H2O = CeHnOe + 6 O2 



(glucose + oxygen) 



CeHi206 = CeHioOs + H2O 



(starch + water) 



While the starch is made in the leaves it cannot be dis- 

 tributed in this form to other parts of the plant, as starch 

 is insoluble. It is therefore first converted into sugar 

 and in this form is distributed to the stem, roots, ear, or 

 wherever needed for growth. The juice of a green maize 

 stem may contain 10 per cent or more of sugar during the 

 earing season, when it is being transported from leaves to 

 stem and ear. This soluable sugar may be converted 

 into many forms of carbohydrate material, as fiber or 

 starch. In the ear it is principally deposited again as 

 starch. 



40. Growth. — Following the plan outlined by Sachs, 

 the growth of a maize plant may be divided into three 

 distinct phases, as : — 



1. The earl}'' growth period (embryonic), in which the 

 rudiments of new organs are formed. 



2. Elongation of the already formed embryonal organs. 



3. Period of internal development. 



The first period covers about the first three weeks of 

 growth. A plant three weeks old will have all parts, as 

 the full number of leaves and nodes, most of the main 

 roots, and embryonic tassel, ears, and tillers. From this 

 time on, growth consists principally of the elongation 

 and development of these parts. Later there is a third 

 phase, that of internal development, as the depositing 

 of starch in the ear and the strengthening of fibrous 

 tissues. 



