10 



number and the tops of the baskets sealed to prevent evap- 

 oration from the surface of the soil. This '^as done as 

 follows : A circular piece of paper having a diameter a 

 little less than that of the basket was dipped in paraffin 

 and a slit of sufficient length and width to admit the 

 young plants 'vas out into it. Previous to sealing a layer 

 of fine sand, about one-fourth inch in thickness, was 

 added to each of the baskets to aid in preventing evapora- 

 tion from the surface of the soil. The paper ^as then 

 adjusted and fastened in place by rixnning melted paraffin 

 around the edge, thus cementing it to the sides of the 

 basket. 



The aiaoujit of paraffin added was determined by ':^eigh.- 

 Ing the baskets before and after sealing. The difference 

 added to the weight at planting gave the final optimum, 



* 



i.e., the weight of the paraffin and basket plus that of 

 the soil in which the moisture content had, by the addition 

 of water, been brot up to the amount considered to be most 

 favorable for the growth of plants. 



The loss of water by transpiration was determined by 

 weighing the baskets at intervals of three or four days. 



