CHAPTER XlV 



PHYSIOLOGY OF THE CORN PLANT 



The life-processes of the corn plant are similar to those 

 described in connection with the cotton plant. Like 

 cotton, the corn plant is composed of a net-work of cell 

 walls — the skeleton, which gives the plant stability. 

 Surrounded by these cell-walls is the protoplasm which 

 assimilates the food and carries out all of the chemical 

 processes necessary for life and reproduction. The food 

 elements are obtained from the soil by absorption through 

 the root-hairs or in the case of the carbon and some of 

 the oxygen by air currents through the breathing .pores 

 of the plant, the stomata. 



COMPOSITION OP THE CORN PLANT 



202. Composition. — The weight of a young rapidly 

 growing corn plant is approximately 90 per cent water 

 and 10 per cent dry matter. As growth advances the per- 

 centage of dry matter increases until at maturity it con- 

 stitutes from 35 to 40 per cent of the total weight of the 

 plant. The composition of this dry matter at different 

 stages in the growth of the corn plant is shown in the table 

 on page 162, which has been compiled from data given 

 in Bulletin No. 175 of the Agricultural Experiment Station 

 of Purdue University. 



The dry matter of a corn plant is much richer in nitro- 

 gen during the early growth of the plant than at later 

 stages of development. This, however, does not neces- 



161 



