98 ANDREWS & BEALS: GrowTH oF ZEA Mays 
the other conditions, except those of aréation and temperature, 
were always the same. 
Fics. 4 and 5 show parts of cross-sections of the roots of Zea 
Mays grown in water cultures. Fic. 4 is part of a cross-section 
of a root which had been aérated, and Fic. 5 is the same of a non- 
aérated root. It will be noticed that the intercellular spaces in 
the non-aérated root are appreciably larger. 


c B : 
Fic. 3. Effects of temperature and aération. Reading from right to left: 
A was not aérated and was exposed to too high a temperature; B was aérated with 
about 48 liters of air in 24 hours, but was exposed to too high a temperature; C wa 
aérated with about 48 liters of air in 24 hours and was exposed to a lower and more 
favorable temperature. 
Specimens of Zea Mays sometimes suffer for lack of aération 
under supposedly normal conditions in the soil. To show this 
point the following experiment was performed. A large bottle 
was cut off near the bottom, a perforated rubber stopper was 
inserted in the neck and a glass tube put through this for the ad- 
mission of air. The bottle was inverted, about 1 cm. in depth of 
melted paraffin poured over the cork to exclude the air and the 
lower part filled with wet sphagnum and this covered over with 
