8 



The n-umerous modifications of desert plants for the 

 purpose of reducing transpiration have been considered by 

 some as evidence that this process is not essential to the 

 growth of plants. It nmst be borne in mind, however, that 

 under these conditions transpiration is still carried on 

 to some extent, furthermore, the conditions are so favorable 

 for excessive transpiration, that ^ere it not for these 

 special adaptations the plants would soon be deprived of 

 their limited supply of ^;ater. 



The experiments described on the following pages were 

 undertaken with a view toward determining what relation, if 

 any, exists between transpiration and growth tonder differ- 

 ent conditions of himiidity. 



Five species of plants wore employed for this purpose, 

 viz., com (State Plint), sunflowers, peas, wheat (Dawson's 

 Golden Chaff) and buclcwheat. 



The plants Yiere grown in wire baskets S inches in dia- 

 meter and S inches deep. The manner of preparation was 

 as follows : The tops of the baskets were first dipped in 

 melted paraffin to the depth of about one inch. This 

 formed a collar around the top which prevented the paraffin 



