TRANSPIRATION AND PHOTOSYNTHESIS IN CORN 



153 



tained in the potometers as moist as the plants would probably 

 stand. This amount was added to potometers for the high moist- 

 ure content. 250 cc. of water was then added to other potome- 

 ters for the intermediate degree of saturation. Soil samples of 

 the three series showed a low content of 25%, a medium of 45% 

 and a high of 65% of the possible saturation. 



Sealing the potometers. The wax-seal method was used. To 

 prepare this seal 80 parts of paraffin (50°) were melted together 



Fig. 2. View in greenhouse showing the cultures, scales, and method of 

 weighing. 



with 20 parts of petrolatum to just above the melting point o 

 the mixture. Small paper collars were made by rolling her 

 barium paper over a glass tube and glueing it in the form of the 

 tube. When the glue had set the paper tube was removed and 

 cut up into 2 cm. lengths. One of these collars was put around 

 each plant and pressed slightly into the soil to give it stability. 

 Sufficient of the wax was poured on each potometer to give a seal 

 of 5 mm. thickness. The crock was rocked slightly to insure a 



