179 



The following- table gives the height of the plants at different 

 stages of growth: 



Aerated. Nonaerated. 



2 days 2.8 cm. 1 . 9 cm. 



3 days 5.9 cm. 4 . 7 cm. 



6 days .• 14 . 50 cm. 12 . 00 cm. 



8 days 25.00 cm. 23.00 cm. 



11 days 28 . 00 cm. 24 . 00 cm. 



15 days 37.00 cm. 33.00 cm. 



20 days 47.00 cm. 37.00 cm. 



26 days 65.00 cm. 46.00 cm. 



F^S- 3- 



Effect of nonacration on roots of Zea Mays. 



After three months' growth in the greenhouse under as nearly 

 normal growing conditions as possible, the plants were removed and 

 burned. The ash of the aerated plant including the roots weighed 2.182 

 grams, while the ash of the nonaerated amounted to 1.303 grams. 



A cross-section of a root when magnified showed that the cortex 

 cells of the aerated plant (Fig. 2) were uniform in size with no con- 



