CHARACTERISTICS OF SOILS 



17 



(See 



seems to reduce the vitality of the resulting plants. 

 Figs. 3, 4, 5, and 6.) 



23. Ventilation and root action. In the absence of 

 oxygen, the roots of common plants not only cannot per- 

 form their functions, but they quickly die. If all the 

 roots die, the remainder of the plant also dies, and if any 



FIG. 5. Effects of ventilation on germination. Same as Fig. 3, 11 

 days from planting ; 4 days after the excess of water had been re- 

 moved from right jar. Fifty per cent only of the kernels have 

 germinated. In the upper right quarter of the cut is shown a ker- 

 nel of corn with the embryo exposed. 



considerable part of the root system is destroyed, the 

 remainder of the plant must suffer, even if it is not killed. 

 Most crops drown very quickly, for the same reason that 

 animals do. Mention was made in paragraph 16 of the 

 great development made by the root system of the corn 

 plant. The root systems of all our crops are extensive. 

 In the absence of oxygen, the roots die. When the supply 



