5°° 



BOTAXICAL GAZETTE 



[DECEMBER 



response. The formation of the root hair is inhibited by removing 

 the covers of the Petri dishes in which the seedlings are growing. 

 Regions of no root hairs, corresponding to the growth made during 

 the removal of the cover, followed in regions of hair formation at 

 the period of its replacement. 



A series of corn seedlings was grown in air of a known moisture 

 content. This was controlled by percentage solutions of sulphuric 

 acid. The corn was soaked for 24 hours and then hung on cork 

 plates in bottles which were one-third filled with the varying 

 solutions. The bottles, which were corked and paraffined, were 

 all placed in a water bath kept at 24°C. The measurements in 

 table V represent in each case the average of 5 sets. 



Table V shows that the cutting down of the moisture content 

 affects the length of the root hair more than the length of the root 

 or the diameter. 



2. IN LIQUID MEDIUM 



a) The physical character of the walls. — There is a variation in 

 the wall of the corn in different media. In moist air the wall is 

 uniform ; in water when formed the hair is thickened at the tip. 



b) The chemical nature of the walls. — The chemical study of the 

 walls is under investigation. 



